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P A R T threeClinicalCharacteristics ofNeuromuscularAnomalies of theEye

C H A P T E R 16Esodeviations

Esodeviations are caused by innervational ormechanical factors or a combination of both.

The various theories for the etiology of strabismusare reviewed in Chapter 9. As is true with otherforms of strabismus, an esodeviation may be con-trolled by fusional divergence (esophoria), inter-mittently controlled (intermittent esotropia), ormanifest (esotropia). In addition to the differencesin etiology, other variable characteristics of esode-viations include their state of comitance, the pres-ence of sensorial adaptations, the age of the pa-tient at the onset, the mode of onset, the size ofthe angle of strabismus, and the state of fixationbehavior (unilateral or alternating). Thus, esodevi-ations are difficult to classify and are never en-tirely accurately classified, since the various char-acteristics may overlap in a single group ofesotropes. For instance, it is an accepted fact thatthe characteristics of infantile esotropia are fairlyuniform in most patients and are different in thosewith accommodative esotropia. Yet, accommoda-tive factors may become superimposed in patientswith essential infantile esotropia. These reserva-tions notwithstanding, we have found the classifi-cation of esodeviations shown in Table 16–1 to beuseful for clinical purposes and as a guideline forthe student.

Not all forms of esodeviations listed in Table16–1 are discussed in this chapter. Esotropia asso-ciated with A and V patterns is covered in Chapter19, and the reader is referred to Chapter 20 for adiscussion of paralytic esotropia, to Chapter 21for descriptions of cyclic esotropia and esotropiacaused by entrapment of the medial rectus muscle

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or as part of the Duane retraction syndrome, toChapter 22 for divergence insufficiency, and toChapter 23 for a discussion of the nystagmusblockage syndrome.

Esophoria and IntermittentEsotropia

Etiology

The etiology of latent or intermittent deviations isnot qualitatively different from that of manifestdeviations (see Chapter 9). Accommodative, non-accommodative, and other innervational (dy-namic) factors may be involved.

Clinical Signs

As pointed out in Chapter 8, true orthophoria(i.e., the absence of heterophoria at any fixationdistance and in any gaze position) is a rarity.Esophoria of a small degree is in fact a commonfinding in a normal population. Scobee254 statedthat the average normal degree of heterophoria atinfinity, as determined with a Maddox rod, is 1.4�

and also noted reduced stereoacuity in patientswith intermittent esotropia, exotropia, and esopho-ria. In our experience, this symptom is frequentlyassociated with the intermittency of a deviation,but it is rarely a prominent clinical symptom inpatients with a well-compensated heterophoria.The signs and symptoms of heterophoria are dis-cussed in Chapter 10.

312 Clinical Characteristics of Neuromuscular Anomalies of the Eye

TABLE 16–1. Classification of Esodeviations

I. Comitant esodeviationsA. Accommodative esotropia

1. Refractive accommodative esotropia (normalAC/A)

2. Nonrefractive accommodative esotropia (highAC/A)

3. Hypoaccommodative esotropia (reduced NPA)4. Partially accommodative esotropia

B. Nonaccommodative esotropia1. Infantile esotropia2. Nonaccommodative convergence excess

(normal AC/A)3. Acquired (basic) esotropia4. Acute-onset esotropia5. Divergence insufficiency or paralysis*6. Cyclic esotropia*7. Recurrent esotropia

C. Microtropia1. Primary microtropia2. Secondary microtropia

D. Nystagmus ‘‘blockage’’ syndrome*II. Incomitant esotropia*

A. ParalyticB. Nonparalytic

1. A- and V-pattern esotropia2. Retraction syndrome3. Mechanical-restrictive esodeviations

a. Congenital fibrosis of extraocular musclesb. Acquired restriction (endocrine myopathy,

trauma to orbital wall, excessive resectionof medial rectus muscle(s), myositis,strabismus fixus)

III. Secondary esodeviationsA. SensoryB. Consecutive

AC/A, accommodative convergence/accommodation ratio; NPA,reduced near point of accommodation.

*Forms of esotropia discussed in other chapters of this book.

Symptoms

Unless a heterophoria is intermittent, in whichcase the patient may be aware of periodic doublevision, the symptoms are mainly asthenopic (seeChapter 10) and related to visual demands madeon the eyes. In other words, asthenopic complaintsoccurring in the morning or after periods of restare rarely caused by heterophorias. Whether aheterophoria becomes symptomatic or is well tol-erated by the patient depends largely on the fu-sional reserve (i.e., in the case of esophoria, onthe amplitude of fusional divergence). The pointhas been made (see p. 206) that the heterophoricposition must be taken into account when measur-ing fusional vergences with rotary prisms.

Sensorial Adaptation

Sensorial adaptation is not difficult to explain inheterophoric subjects with intermittent deviations.

Suppression or anomalous retinal correspondencedevelops in young patients as an adaptation todiplopia that is present during periods when theocular deviation is manifest.

Flynn and coworkers93 reported on foveal sup-pression under binocular conditions of viewing inpatients with heterophorias and intermittent het-erotropias. Using entoptic images (Haidinger’sbrushes and afterimages), they demonstrated intheir patients not only foveal suppression but alsowhat must be interpreted as instability of fovealvisual directions. In fact, in several instances aminute angle of anomalous retinal correspondencewas demonstrated. These authors emphasized thatsuppression in heterophoria may present a realobstacle to a functional cure. Stangler’s273 observa-tion that heterophoric patients were unsuccessfulin superimposing a vertical afterimage producedin one eye on a real object fixated by the othereye also indicates an instability of foveal visualdirections in this condition.

The question must be asked, Why do hetero-phoric subjects develop suppression or evenanomalous retinal correspondence if the deviationis controlled by fusion, and what is the purposeof sensorial adaptation under such circumstances?There are two possible answers. First, the devia-tion in such patients at times and under certaincircumstances may become manifest (intermittentstrabismus), making sensorial adaptation neces-sary to avoid diplopia. If fusion is artificially dis-rupted, as shown in the tests used by Flynn andcoworkers and by Stangler, suppression and anom-alous retinal correspondence will become mani-fest. Second, in heterophoric patients with sup-pression, an intermittent heterotropia may be onthe verge of developing. It is possible that suppres-sion may then prevail to avoid foveal diplopia,and fusion is maintained by peripheral retinalstimulation only. We believe that deficient stereop-sis in heterophoric patients may be explained onthe basis of this suppression since it is known thatfoveal suppression of one eye under binocularconditions of viewing will cause a decrease instereoacuity. Shippman and Cohen260 suggestedthat in patients with esophoria, stereoacuity isbetter with uncrossed than with crossed disparityas determined by means of the Wirt stereotest.

Diagnosis

The diagnosis of heterophoria is discussed inChapter 12, and only a few additional comments

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need to be made here. The clinician must be awarethat heterophorias can be measured with only ap-proximate accuracy. For instance, the Maddox rodtest measures the basic deviations when fusion isdisrupted, but it does not determine that part ofthe deviation caused by dynamic factors such asaccommodative convergence. Thus, in a sympto-matic patient with esophoria, the deviation mustbe measured with the prism cover test at 33 cmwhile the patient reads letters of an appropriatesmall size at random. In fact, failure to controlaccommodation at near fixation may lead to anerroneous diagnosis, as illustrated by the follow-ing case.

CASE 16–1

A 27-year-old woman who had suffered a mild con-cussion in an automobile accident 6 months earliercomplained of intermittent diplopia at distance andblurred vision when trying to read and related thesecomplaints to the injury. Litigation of this case involv-ing a considerable sum of money was pending. Ex-amination by another ophthalmologist had revealeda visual acuity of 6/6 OU and entirely normal ocularfindings except for an intermittent esotropia of 20�

at distance fixation. She was reported to have ortho-phoria at near fixation. Ductions and versions werenormal. A diagnosis of ‘‘divergence paralysis,’’ prob-ably related to the trauma, was made. An extensiveradiographic survey of the skull and a neurologicexamination were ordered. When this patient wasseen by us in consultation, the same measurements(20� intermittent esotropia) were obtained at dis-tance fixation. At near fixation the alternate covertest failed to reveal a shift; however, the patientindicated that the fixation target held at 33 cm be-fore her eyes appeared blurred. When she wasasked to identify small letters at that distance, visionsuddenly cleared and an intermittent esotropia of25� appeared. On further questioning, the patientadmitted that she sometimes saw double at bothdistance and near fixation and that she had learnedto avoid diplopia at near vision by ‘‘relaxing hereyes.’’ The diagnosis of divergence paralysis couldno longer be supported. We believed that the pa-tient had an esophoria and that the deviation at nearwas initially missed because the patient was notaccommodating on the fixation target. She wastreated with base-out prisms, which almost instantlyeliminated her complaint, and a resection of bothlateral rectus muscles eventually brought a good re-sult.

Case 16–1 illustrates that some patients preferto see blurred and single by relaxing their accom-modation rather than sharp and double. When

measuring heterophoria with the prism and covertest, it is important to repeatedly cover each eyefor several seconds and to switch the cover rapidlyfrom eye to eye to suspend completely the influ-ence of fusional vergence (see Chapter 12). Thistechnique will often reveal larger amounts of basicesodeviation than originally suspected. In doubtfulcases, prolonged monocular occlusion for daysor even weeks has been advocated184 to discloseheterophorias that are not at once evident duringthe alternate cover test. It is erroneous to assumethat momentary disruption of fusion by coveringeach eye in a rapid fashion will totally exclude astrong innervational tonus such as the one elicitedby the compulsion to fuse.

Once the type and size of a heterophoria havebeen determined, the patient’s ability to cope withan ocular imbalance must be evaluated by measur-ing fusional amplitudes (see Chapter 12).

Therapy

The principle of treating esophoria and intermit-tent esotropia is the same as for all other forms oflatent and intermittent deviations, that is, to createconditions that will allow the patient to enjoycomfortable and functionally complete binocularvision. Depending on the individual case, this goalcan be approached by using one of several modesof therapy. Before discussing these methods, wewould again like to stress that esophoria per serequires no therapy unless asthenopia or evidenceof deterioration of binocular functions also is pres-ent.

A symptomatic esophoric patient in whom re-fraction reveals a significant amount of hyperme-tropia (at least �1.25D sph) is treated by fullcorrection of the hypermetropic refractive error inthe same manner as in an esotropic patient. Pa-tients with a high accomodative convergence/ac-comodation (AC/A) ratio and a symptomatic eso-phoria without hypermetropia may be consideredfor bifocal lenses or miotics. For details regardingthis mode of therapy, see Chapter 24.

Prisms base-out may be helpful as a ‘‘crutch’’in regaining visual comfort in patients with nonac-commodative esophoria. When prescribing prismsfor esophoria, however, one must clearly under-stand that this mode of therapy does not curethe ocular imbalance; it only creates temporaryconditions that enable the patient to cope morecomfortably with the deviation. Correction of onlyone half to one third of the angle of deviation


with prisms is advisable to prevent total inactivityof the fusional divergence mechanism. Since par-tial or complete correction of esophoria withprisms will place fewer or no demands on fusionaldivergence, such patients may become increas-ingly dependent on their prisms. The use of cor-recting prisms, particularly in patients with esode-viations of dynamic origin, will result eventuallyin an increase of the esophoria, and prisms ofincreasing power will be required to create visualcomfort. These objections notwithstanding, thereis a place for prismatic correction in elderly pa-tients with symptomatic esophoria who do notrespond to orthoptics. In younger patients, we useprisms occasionally in those in whom fusion mustbe maintained until surgery can be performed(prismatic orthophorization).

Surgery should be considered only when thesize of the deviation in a patient with esophoriaor intermittent esotropia falls within the range (atleast 12�) that can be corrected without fear ofovercorrection. Prerequisites for planning surgeryare stability of the deviation after full correctionof the hypermetropic refractive error and the pres-ence of muscular asthenopia. When the decisionhas been made to operate, the surgeon shoulddetermine the extent of surgery necessary andselect the muscles to be operated on in the usualmanner and as outlined in Chapter 26.

On numerous occasions, we have witnessedunwarranted timidity in the surgical approach tolatent or intermittent esodeviations (or exodevia-tion, for that matter), apparently based on themisconception that such patients have ‘‘just’’ aheterophoria (as opposed to a heterotropia), andtherefore lesser amounts of surgery are required.This attitude is erroneous, of course, and causesundercorrections that, because of their small size,may be difficult to control by additional surgery.The amount of surgery must be aimed at the basicdeviation and on the goal to align the eyes, re-gardless of whether it is a latent, intermittent, ormanifest deviation! It is preferable to establish asecondary exophoria rather than be left with aresidual esophoria. Convergence fusional move-ments and also voluntary convergence are moreeffective than the divergence mechanism in keep-ing such a residual heterophoria in check.

A conservative approach is indicated whenconsidering surgery for esophoric patients beyondthe age of 50 years. In younger patients, smallsurgical overcorrections present no problem andusually are easily compensated for by fusional

convergence. On the other hand, a consecutiveexodeviation, regardless of how small, can causeconsiderable and often insurmountable difficultiesin older persons. The elasticity of the fusionalapparatus in overcoming motor obstacles in binoc-ular vision tends to decline with advancing age.Experience has taught us to treat such patientswith prisms; surgery should be contemplated onlyreluctantly and after all other therapeutic possibili-ties have been exhausted.

Accommodative Esotropia

An esotropia caused by an increased accommoda-tive effort or an abnormally high AC/A ratio isreferred to as ‘‘accommodative’’ esotropia. How-ever, several subgroups of accommodative esotro-pia exist and must be clearly differentiated as eachrequires different clinical management.

Refractive AccommodativeEsotropia (Normal AC/A Ratio)

Definition

Refractive accommodative esotropia is defined asan esotropia that is restored to orthotropia at allfixation distances and in all gaze positions byoptical correction of the underlying hypermetropicrefractive error.

Etiology

The relationship between accommodation andconvergence and the role of an uncorrected hyper-metropic refractive error in causing a comitantesodeviation was discussed earlier (see p. 139).At this juncture it is useful to summarize theetiologic components and to mention why somepatients with uncorrected hypermetropia do andothers do not develop esotropia (Fig. 16–1). Mostpatients with uncorrected hypermetropia will at-tempt to clear the image blur by increasing accom-modative effort that will, in turn, cause excessiveaccommodative convergence. If fusional diver-gence is insufficient to compensate for this im-pulse to converge the eyes (Fig. 16–1A) and inthe presence of a normal or high AC/A ratio,esotropia will develop. If fusional divergence am-plitudes are sufficient to cope with the inducedesodeviation, an esophoria will be produced (Fig.16–1B). In the presence of a low or flat AC/A

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FIGURE 16–1. Consequences ofuncorrected high hypermetropia.AC/A, accommodative conver-gence–accommodation ratio. Forexplanation, see text. (Modifiedfrom Noorden GK von, HelvestonEM: Strabismus: A Decision Mak-ing Approach. St Louis, Mosby–Year Book, 1994, p 95.)

ratio, the patient may remain orthotropic since theconvergence induced by excessive accommoda-tion is normal or even subnormal209 (Fig. 16–1C).Finally, some patients with uncorrected high hy-permetropia may remain orthotropic because theyprefer blurred vision over the constant effort toaccommodate excessively. Such patients may de-velop a mild form of pattern deprivation amblyo-pia in both eyes (ametropic amblyopia; see p. 252)or an accommodative deficiency with a reducednear point of accommodation,209 or both (Fig. 16–1D). Whether the visual system reacts with esotro-pia and clear vision or with orthophoria andblurred vision may depend less on the degree ofhypermetropia than on the child’s personality. It isour impression, which needs to be substantiatedby an appropriate study, that the former groupoften encompasses fastidious and exacting chil-

dren and that the latter group is more relaxed andeasygoing, as highlighted by Case 16–2.

CASE 16–2

An 8-year-old girl and her 6-year-old brother werebrought to our office for an eye examination. Thegirl had a history of a gradual onset of esotropia atthe age of 3 years and had worn glasses since thattime. The boy had no apparent strabismus, but hadfailed a school vision screening test. The girl had anesotropia of 35� at near and distance fixation withoutglasses. She was wearing a hypermetropic correc-tion of �5.00 sph in both eyes, which fully correctedher esotropia. Her corrected visual acuity was 6/6 ineach eye. The boy had the same refractive error(confirmed by cycloplegic refraction in both chil-dren), but was orthophoric with and without glasses.


His best corrected visual acuity was 6/15 in eacheye, which improved to 6/9 after wearing glassesfor 6 weeks. His AC/A ratio, determined by thegradient method over a range of 6D was 0. The girlwas a keen observer and asked numerous questionsduring the examination. The boy remained silentand rather passive. When we asked the mother todescribe the most pertinent personality traits of herchildren, she replied, ‘‘She is the absolute perfec-tionist, meticulous in every respect. He is com-pletely relaxed, quite sloppy, and does not careabout a thing in the world.’’

Clinical Characteristics

As a rule, the onset of accommodative esotropia,whether refractive or nonrefractive, is between theages of 2 and 3 years. The onset also may bedelayed until adolescence or even adulthood,when it is often precipitated by a brief period ofocclusion (see acute strabismus, p. 338). We havealso seen children of 1 year or less with all theclinical features of accommodative esotropia, andPollard237 reported two infants with hypermetropiain whom esotropia developed at 41⁄2 and 5 monthsof age (see also Coats and coworkers49 and Haver-tape and coworkers111) and whose eyes becamecompletely aligned following correction of therefractive error. Baker and Parks14 reported addi-tional cases and pointed out that after initial con-trol of esotropia by means of glasses, approxi-mately 50% of these patients developednonaccommodative esotropia. In such cases, surgi-cal intervention may become necessary. These au-thors also reported that bifoveal fusion does notdevelop in patients with refractive accommodativeesotropia of early onset (monofixation syndrome;see p. 341) and that their ocular deviation is simi-lar to that in patients with essential infantile eso-tropia. Whether this sensory deficit can be relatedto how long the esotropia had been present beforecorrection with glasses is unclear. The observa-tions of these investigators show that the earlierviewpoint, that accommodation is inactive duringinfancy, can no longer be upheld. In fact, Haynesand coworkers113 showed that accommodation mayreach the adult level by the fourth month of life.

When refractive accommodative esotropia ispresent, the ocular deviation is usually variableand larger at near than at distance fixation. Thevariability of the angle of deviation depends onthe general state of the patient (alert or fatigued)

and on the amount of accommodation exerted ata given moment. The evolution of accommodativeesotropia usually is gradual, and most patientspass through a stage of intermittent strabismus.Asthenopic symptoms, complaints about intermit-tent diplopia, or closure of one eye when doingclose work commonly occurs during developmentof the disease.

Therapy

The prognosis for restoration of normal binocularfunction in refractive accommodative esotropia isusually excellent if normal binocular functionsexisted before the onset of the deviation. Fullcorrection of the hypermetropic refractive error,determined by cycloplegic refraction, is usuallyall that is required initially for rehabilitation. Pa-tients who have never worn glasses may initiallycomplain about blurring of vision with their opti-cal correction. In this instance a brief period ofatropinization to relax accommodation may be re-quired before the glasses are tolerated. Thecycloplegic refraction is repeated annually, andthe glasses are adjusted when necessary. Althoughthere is a tendency for hypermetropia to decreaseas a child gets older the majority of patients re-quire glasses well into adolescence283 and beyond.

If the distance deviation is reduced or elimi-nated by glasses and esotropia remains at nearfixation, the AC/A ratio is higher than normal(nonrefractive accommodative esotropia), or thepatient has a nonaccommodative convergence ex-cess. If the glasses only partially reduce the angleof strabismus at near and distance fixation, thenthe strabismus is not purely refractive-accommo-dative in nature (partially accommodative esotro-pia).

Abraham1 has recommended that miotics besubstituted for glasses in certain patients with re-fractive accommodative esotropia. We ordinarilydo not advocate prolonged miotic therapy for thiscondition except in hyperactive or extremely un-cooperative children for whom the incessant re-placement of broken or lost spectacles imposes anunbearable financial burden on the parents. Wehave found it useful, however, to prescribe mioticsin lieu of glasses for limited periods during thesummer months for children who spend the holi-days at the beach or long hours in or near aswimming pool. (For a general discussion of the

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use and action of miotics in strabismus, see Chap-ter 24.)

Dyer83 advocated surgery in lieu of glasses orto reduce a strong correction. He stated that ‘‘attimes the risk of a subsequent exodeviation isworthwhile when the patient can enjoy years ofstraight eyes without glasses or much weaker cor-rection in the glasses.’’ This controversial philoso-phy never found a following in this countrybut has been reendorsed in recent years byGobin,100, 101 Berard and coworkers,17 and othersin Europe.41 Under the influence of these authorsit has become common practice in some countriesto operate for fully refractive accommodative eso-tropia, that is, an esodeviation that is fully offsetby the appropriate optical correction. Gobin101

stated that he no longer believes ‘‘that hypermetro-pia is the cause of convergent squint’’ and that‘‘the accommodative component of the squint dis-appears’’ after surgical restoration of binocularvision. Among the reasons given by the propo-nents of surgery is that many patients correctedwith glasses will show a progressive deteriorationof binocular vision.88 It has also been claimedthat cyclovertical incomitances such as A and Vpatterns and dysfunctions of the oblique musclesoccur frequently in patients with refractive accom-modative esotropia, present significant obstaclesto fusion, and must be corrected by surgical desag-ittalization of the oblique muscles.90 However, nodata have been presented to substantiate theseclaims. On the contrary, several independent stud-ies have established that functional deteriorationof fully refractive accommodative esotropia oc-curs infrequently76, 210, 270 and that the diagnoses ofdysfunctions of the oblique muscles and of Aand V patterns in these patients are caused byinadequate diagnostic and measurement tech-niques.210

Moreover, Schiavi and coworkers253 haveshown that inferior oblique overaction is not acommon sign of refractive accommodative esotro-pia. When present, it does not necessarily heralda negative prognosis for preservation of normalbinocularity through glasses. Inferior obliqueoveraction can develop after loss of alignment insome but not all the decompensated patients. Noevidence can be found for a cause-effect relation-ship between oblique muscle dysfunction and lossof binocularity in refractive accommodative eso-tropia.

In view of the foregoing we conclude, there-

fore, that the case for surgery in this condition hasnot been proved.90, 145, 210 We reject this therapeuticapproach, which is contrary to physiologic princi-ples and clinical experience and may be harmful,as shown by the following case.

CASE 16–3

A 25-year-old female schoolteacher consulted uswith severe asthenopic complaints. She had wornglasses since early childhood to correct for an eso-tropia, which was well controlled with spectaclescorrection. She gave no history of having sufferedvisual discomfort in the past except when taking herglasses off, which caused her to see double andforced her to close one eye. She went to a ‘‘strabis-mus center’’ 6 months ago where she was offeredsurgery as an alternative to her glasses. The patientwas not advised of the possible unfavorable conse-quences of such an operation and enthusiasticallyagreed to have the procedure done. After musclesurgery her eyes were aligned and she no longersaw double without glasses. However, soon after-ward she developed severe visual discomfort con-sisting of headaches, tearing, and nausea after read-ing without glasses for longer than 10 minutes. Herold glasses relieved these symptoms, but she hadto close one eye since she now saw double withher spectacles. Because of her visual difficulties,she was unable to continue teaching school, anoccupation that she had enjoyed very much. Hercycloplegic refraction was �4.75 sph in each eye.She was orthotropic without glasses and developed18� exotropia at near and distance fixation with herglasses.

We predict that the woman in Case 16–3 isbut one of numerous unhappy patients likely topopulate the waiting rooms of ophthalmologists inthe future if the practice of operating for esotropiathat has already been fully corrected with glassesor contact lenses continues.

The use of excimer laser photokeratectomy andparticularly LASIK (laser-assisted in situ kerato-mileusis) in the treatment of accommodative stra-bismus is being discussed with increasing fre-quency. At this stage of our knowledge and inview of the lack of long-term results with this andother keratorefractive procedures we are opposedto this treatment in the pediatric age group.

In the rare event of deterioration despite a satis-factory initial response to optical correction of thehypermetropia, a recession of both medial rectusmuscles will restore fusion in most instances.


Nonrefractive AccommodativeEsotropia (High AC/A Ratio)

Definition

Nonrefractive accommodative esotropia is definedas an esotropia greater at near than at distancefixation, unrelated to an uncorrected refractive er-ror, and caused by an abnormally high AC/A ratioin the presence of a normal near point of accom-modation.


Nonrefractive accommodative esotropia occurs inpatients with emmetropia, hypermetropia, or myo-pia; however, moderate degrees of hypermetropiaare encountered most frequently. The etiology isunrelated to the underlying refractive error but isclosely linked with an abnormal synkinesis be-tween accommodation and accommodativeconvergence—the effort to accommodate elicitsan abnormally high accommodative convergenceresponse. If motor fusion can cope with the in-creased convergence tonus at near fixation, anesophoria results. If motor fusion is insufficient,nonrefractive accommodative esotropia will be-come manifest. Unlike hypoaccommodative eso-tropia, discussed in the next section, the nearpoint of accommodation is normal for the age ofthe patient.

Parks223 reported an abnormally high AC/A ra-tio in 46% of 897 children with comitant esotro-pia. The age of onset of accommodative esotropiain this series ranged from 8 months to 7 years,with an average of 30 months. However, Parksbased the diagnosis of a high AC/A ratio on theheterophoria rather than on the gradient method.As pointed out earlier (see p. 91), the widelyused and, in our opinion, inadequate heterophoriamethod to determine the AC/A ratio does notdistinguish between a high AC/A ratio and nonac-commodative convergence excess. Thus, the pa-tient group reported by Parks is not clearly de-fined. It is our clinical impression that mostpatients with nonrefractive accommodative esotro-pia present between the ages of 6 months and3 years.

The diagnosis of nonrefractive accommodativeesotropia is based on the presence of a significantesodeviation at near fixation on an accommodativefixation target (see Chapter 11) with the refractiveerror fully corrected and the presence of a highAC/A ratio as established with the gradient

method to distinguish this condition from nonac-commodative convergence excess (see below). Thenecessity of measuring the angle of deviation atnear fixation with accommodation fully controlledin patients with all types of strabismus, especiallyin this group of patients, cannot be overempha-sized. The reason is that children with accommo-dative esotropia may manage to keep their eyesaligned at near fixation by accommodating onlypartially or not at all (see Case 16–1). The use ofa fixation target that requires full accommodationto identify small details will eliminate this fre-quent cause of diagnostic error.

Confusion may arise when diagnosing an eso-tropia with a high AC/A ratio and an esotropiawith a V pattern (see Chapter 19) if the angle ofstrabismus is measured at distance fixation withthe eyes in primary position and at near fixationwith the gaze lowered. In esotropia with the Vpattern, the deviation increases characteristicallyonly in downward gaze regardless of whether thepatient fixates at near or distance. With an accom-modative esotropia, the deviation will increase atnear fixation regardless of the position of the eyesin which the angle of strabismus is measured.

Therapy

Since the near deviation is the primary obstacle tonormal binocular vision in patients with nonrefrac-tive accommodative esotropia, the conditions fortreatment with bifocal lenses are ideal. For detailsregarding this therapy see Chapter 24.

Attempts have been made to substitute progres-sive lenses for bifocal lenses. However, unless thepatient looks maximally downward, the add in thelower portion of the lens is too low and accommo-dation is still being employed in downward gaze.Children may not be inclined to look maximallydownward during visual activities at near and al-though cosmetically preferable, we feel that pro-gressive lenses should not be prescribed for thetreatment of accommodative esotropia.

Long-acting anticholinesterase drops have alsobeen advocated but because of side effects aresive lenses for bifocal lenses. However, unless theThe principles of bifocal therapy are discussed inChapter 24. The majority of patients with nonreda-tion is still being employed in downward gaze.bifocals; however, we also have observed a slowdeteriorating course of the disease.217 In such in-stances and after a patient has initially regainedfusion and stereopsis at near fixation with bifocal

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correction, the near deviation may increase with-out obvious cause, becoming first intermittent andeventually manifest in the course of several years.

Cycloplegic refraction performed at that pointmust exclude the possibility of an increase ofthe hypermetropic refractive error. In that case,stronger lenses should be prescribed. If this doesnot correct the deviation, then such patients re-spond well to a recession or posterior fixation ofboth medial rectus muscles or a combination ofboth.176, 234, 272, 275 The amount of surgery should bebased on the near deviation without fear of caus-ing an overcorrection at distance fixation. Moststudies of the results achieved with either of theseprocedures do not distinguish between accommo-dative and nonaccommodative convergence excess(see below), making it somewhat difficult to eval-uate such reports. We have been satisfied with theresults of recession of both medial rectus musclesand no longer use retroequatorial myopexy for thiscondition.

Hypoaccommodative Esotropia

Definition

Hypoaccommodative esotropia is defined as anesotropia greater at near than at distance fixation,unrelated to an uncorrected hypermetropic refrac-tive error and caused by excessive convergencefrom an increased accommodative effort to over-come a primary or secondary weakness of accom-modation.


Costenbader52 drew attention to this special formof esotropia for which he suggested the descriptiveterm hypoaccommodative. This form is character-ized by a small refractive error, a remote nearpoint of accommodation, a small deviation at dis-tance fixation, but a large esotropia at near fixa-tion. He stated that routine testing of the nearpoint of accommodation in strabismic patients re-vealed a surprisingly large number in whom thenear point was recessed farther than one wouldexpect from the patient’s age. According to Cos-tenbader, such patients must exert an excessiveaccommodative effort to clear their vision at nearand, in so doing, exhibit excessive and undesirableconvergence. Clearly, this form of esotropia isaccommodative, even though its mechanism dif-fers from that discussed above in connection with

refractive accommodative and nonrefractive ac-commodative esotropia.

Muhlendyck192, 193 confirmed Costenbader’sconcept of hypoaccommodative esotropia and re-ported patients with reduced accommodativerange, an esotropia at near fixation, asthenopiaafter prolonged periods of reading, and temporaryblurring of vision after switching from near todistance vision. Muhlendyck pointed out that thiscondition may be one of the causes of readingdifficulties in schoolchildren and recommendedplus lenses for near vision. According to Muhlen-dyck, the prevalence of hypoaccommodative eso-tropia was 3.7% in 3929 patients with strabismus.With the exception of Muhlendyck’s work, hypo-accommodative esotropia has received no atten-tion since Costenbader’s original description.

For many years we were skeptical of the exis-tence of this entity until we became aware thatchildren with an accommodative esotropia whohad been treated with bifocals for a long time mayhave an abnormally low near point of accommoda-tion.208 It may be argued that this accommodativeweakness may have been caused by prolongedbifocal wear but, alerted by this finding, we sincehave identified children with an esotropia at nearfixation who had a reduced near point of accom-modation prior to bifocal therapy. Moreover, Muh-lendyck and Goerdt194 reported the near point ofaccommodation unchanged in children with hypo-accommodation after bifocal wear of 6 years orlonger. On the basis of these observations webelieve that Costenbader’s original concept needsto be reinvestigated because it may well deserveits proper place in a classification of esodeviations.The findings that not all children with a remotenear point of accommodation become esotropic atnear, that a reduced near point of accommodationmay actually be associated with convergence in-sufficiency and exophoria,214, 215 and that the in-creased accommodative effort associated with be-ginning presbyopia rarely produces a manifestesodeviation do not necessarily present argumentsagainst the validity of Costenbader’s theory.

Partially AccommodativeEsotropia

Definition

An esotropia is partially accommodative when ac-commodative factors contribute to but do not ac-count for the entire deviation.



Esodeviations of refractive or nonrefractive ac-commodative etiology do not always occur in their‘‘pure’’ forms. A residual esotropia may exist de-spite full correction of a hypermetropic refractiveerror or prescription of bifocal lenses or mioticsor both. As a matter of fact, the majority ofpatients with esotropia have a mixed type that ispartially accommodative and partially nonaccom-modative. This is especially so in essential infan-tile esotropia.123, 242

Few comments are necessary concerning thisform of esotropia, but two points should be made.First, at times in a child with essential infantileesotropia an accommodative element becomes su-perimposed on the deviation as the child growsolder, often accompanied by a larger hypermetro-pia than was first measured. Indeed, it may be therule that the nonaccommodative element occurredearly in infancy or was connatal, whereas theaccommodative component is a later acquisition.Second, the presence of a nonaccomodative ele-ment should always raise the question that thebasic refractive error is not fully corrected;cycloplegic refraction should be done to rule outthis possibility.

Thus it appears that the nonaccommodative ele-ment in accommodative esotropia resists etiologicclassification. In most instances the deviation isprobably congenital with an accommodative ele-ment becoming superimposed as the child growsolder, but in other cases a nonaccommodative ele-ment develops after initial alignment of the eyeswith glasses or bifocal lenses. With our presentknowledge, we can only postulate that increasedconvergence tonus or mechanical factors such assecondary contractures of the medial rectus mus-cles, conjunctiva, or Tenon’s capsule may playa role.

Therapy

Amblyopia must be eliminated by appropriatetherapy (see Chapter 24), and a full hypermetropiccorrection should be prescribed. Bifocals or miot-ics, or a combination of both, are useless since thedeviation is only reduced but not eradicated. If itis warranted by the size of the nonaccommodativeangle of strabismus, which must be determinedwhile the patient is wearing full correction, sur-gery should be performed to align the eyes. Con-servatism is indicated in hypermetropes of

�4.00D sph or more (see p. 324). We want toreemphasize that only the nonaccommodativecomponent of the strabismus should be correctedsurgically. Special care must be taken to explainthis in great detail to parents, who otherwise mayexpect that glasses will not be required after theoperation.

Nonaccommodative Esotropia

Essential Infantile Esotropia

Definition

We define infantile esotropia as a manifest esode-viation with an onset between birth and 6 monthsof age, and following the suggestion of the Hu-gonniers134, p.208 add the modifier essential to em-phasize the obscure etiology of this condition andto distinguish it from other forms of esodeviationwith an onset at about that time.203 Because infan-tile esotropia is commonly accompanied by a setof other clinical findings (Table 16–2) it is justifiedto speak of the essential infantile esotropia syn-drome.167

Terminology, Prevalence, Etiology

We prefer the term essential infantile esotropiaover the older term congenital esotropia but haveno objection to using both terms interchangeably.

TABLE 16–2. Clinical Characteristics of EssentialInfantile Esotropia

Consistent Findings

Onset from birth–6 moLarge angle (�30�)Stable angle which may increase with timeInitial alternation with crossed fixationOccasionally also very early fixation preferenceNo clinically apparent CNS involvementAsymmetrical optokinetic nystagmus

Variable Findings

AmblyopiaApparently defective abductionApparently excessive adductionUp- or downshoot on adductionA or V patternDVD/DHDManifest-latent nystagmusManifest nystagmus (rare)Anomalous head postureHeredity

CNS, central nervous system; DVD, dissociated horizontal devia-tion; DHD, dissociated horizontal deviation.

Esodeviations 321

The reason for this preference, which has not goneunchallenged,172, 231 is the following. Congenital isdefined as ‘‘existing at or dating from birth.’’296

The fact is that esotropia is rarely present at birtheven though many parents may insist that this wasthe case. Comprehensive and independent studiesof a total of 2200 newborns have shown thatexotropia and, to a much lesser degree, esotropiaoccur commonly in the neonatal period but are, asa rule, transient and disappear by the age of 3months.98, 197, 265, 290 Children who eventually de-velop the essential infantile esotropia syndromemay actually have been exotropic or orthotropicat birth.197 A congenital onset according to thedefinition, if it occurs at all, must be exceedinglyrare. It is of historical interest that the Englishsurgeon Edward W. Duffin commented as early as1840 that he had ‘‘not met with a single case ofcongenital strabismus, though in many instancesthe deformity has been reported to have super-vened a few days after birth. Even children ofparents who are affected with strabismus and inwhom we might conclude it would be hereditary,do not exhibit any appearance of the deformityfor months or perhaps years after birth.’’82

This should not distract from the probabilitythat hereditary factors play a role in the etiologyof this disorder. However, a hereditary componentdoes not make a condition ‘‘congenital.’’ Esotro-pia with an onset after 6 months of age is referredto as early acquired esotropia.

The prevalence of essential infantile esotropiawas once estimated to be 1% of the popula-tion.97, 104 However, the recent comprehensive lon-gitudinal studies of Helveston and his coworkershave established this number to be closer to0.1%.197 Even with this reduced prevalence, essen-tial infantile esotropia is the most common formof strabismus.

The etiology of essential infantile esotropia isunknown, and the various theories have been dis-cussed in Chapter 9. We favor a hypothesis ac-cording to which various strabismogenic forcesimpinge on a sensorially normal but immature andtherefore functionally imperfect visual system. Anormally functioning vergence mechanism is ca-pable of overcoming these forces; delayed devel-opment or a defect of the vergence system is notcapable of overcoming these forces and esotropiaensues.206 This view is shared by other authors.114,

118, 285 This hypothesis is summarized in Figure16–2. It must be emphasized, however, that this ismerely a working hypothesis that may have to be

modified or even abandoned as new informationbecomes available. Several reports,24, 85, 303 ac-cording to which normal binocular vision withrandom-dot stereopsis may occasionally be re-stored by early surgical alignment (even in somepatients who do not undergo operation85), supportour assumption that there is no underlying congen-ital sensory defect preventing a functional cure inthese patients.

Differential Diagnosis

Essential infantile esotropia is not the only formof esodeviation with an onset during the first 6months of life. There are other conditions, sometruly congenital, that is, present at birth, and othersacquired during the first few months of life, likeessential infantile esotropia. Among the congenitaldefects are bilateral abducens paralysis (Chapter20), Duane syndrome type I, and Mobius syn-drome (Chapter 21). Conditions acquired duringthe first few months of life may be sensory esotro-pia (see p. 345), refractive accommodative esotro-pia (see p. 314), the nystagmus compensation(blockage) syndrome (Chapter 23), or esotropiain association with other central nervous systemmanifestations, such as Down syndrome, albinism,cerebral palsy, mental retardation, and so on. Thelatter group deserves to be separated from essen-tial infantile esotropia in otherwise normal chil-dren because the surgical outcome, in our experi-ence and that of others, is less predictable.236


Some disagreement exists among current authorsas to the significance of the clinical characteristicsand their prevalence in patients with essential in-fantile esotropia. These variations can sometimesbe explained by differences in examination tech-niques or by geographic differences. Table 16–2lists what we consider to be the most typicalcharacteristics of this condition, some of whichare more or less consistent; others are variable.Ciancia42 described a group of patients with essen-tial infantile esotropia, latent nystagmus, a headturn toward the adducting eye, and apparentlylimited abduction in both eyes. This has beenreferred to as the Ciancia syndrome. Lang165 em-phasized the frequent association between early-onset esotropia, dissociated vertical deviation, ex-cycloduction of the nonfixating eye, and abnormal


FIGURE 16–2. Hypothesis of the pathogenesis of essential infantile esotropia. OKN, optokineticnystagmus. (Modified from von Noorden GK von, Helveston EM: Strabismus: A Decision MakingApproach. St Louis, Mosby–Year Book, 1994, p 95.)

head posture. In the European literature essentialinfantile esotropia is therefore frequently referredto as Lang syndrome. Both of these contributionsare important because they focused attention onpreviously neglected aspects of essential infantileesotropia. It is questionable, however, whetherthese syndromes represent separate entities andwe believe that they emphasize some of the morevariable features of the infantile esotropia syn-drome (see also Helveston118).

AGE AT ONSET. The age of a child at the onsetof esotropia must be established by history duringclinical examination since children rarely arebrought to an ophthalmologist before 6 months ofage. In evaluating the validity of the history givenby the parents, one should remember that mothersoften tend to overlook strabismus in their childbecause they do not want to believe their babyhas a defect. It is characteristic for the mother to

report that relatives, often the mother-in-law(!), orfriends first remarked on the ocular deviation,although she herself had not noticed it. In othercases the onset actually may have occurred later inlife than the history given by the parents indicates.

Costenbader54 noted the high prevalence ofpseudostrabismus in a group of children with aprimary diagnosis of strabismus (352 of 753 pa-tients) and postulated that children at first mayhave pseudostrabismus that subsequently developsinto an esotropia. In such cases, the history givenby the parents indicates that the onset of esotropiawas at birth rather than at a later date. In thisgroup the prognosis for normalization of binocularfunctions may be significantly better than in pa-tients with a true congenital esotropia since theformer group of patients had an opportunity toacquire binocular single vision before the devia-tion occurred. If the reliability of the history ob-tained from the parents is doubtful, photographs

Esodeviations 323

of the patient are useful in determining whetherstrabismus was present at an earlier age than indi-cated by the parents. Careful investigation forother frequently associated features of essentialinfantile esotropia in most instances will allowone to arrive at the correct diagnosis, even inpatients whose histories are doubtful or in whoma history cannot be obtained, such as adopted chil-dren.

SIZE OF DEVIATION. Unlike esotropia of lateronset, essential infantile esotropia is usually char-acterized by a large deviation of 30� or more.54,

57, 205 Deviations of less than 30� also occur butare less common. The angle of deviation is usuallyquite stable if stability of the angle is defined asinsignificant changes in its size in the course of theexamination and on subsequent reexaminations.Exceptions do occur, especially in patients withsmaller angles of deviation in whom spontaneousresolution of esotropia may occur25 and in thosewith the nystagmus blockage syndrome in whomthe angle is quite variable (see Chapter 23). Theconcept of a stable angle in patients with essentialinfantile esotropia is not shared by all ophthalmol-ogists.69, 123, 165 Clark and Noel46 and Hiles andcoworkers123 described cases of large angle essen-tial infantile esotropia with spontaneous regressionof the angle over 3 years. Such events are rare,however, and Birch and coworkers25 reported sta-bility of the angle in 66 children with essentialinfantile esotropia of 40� or more who were fol-

FIGURE 16–3. Distribution of refractive errors (spherical equivalent) in 408 patients with essentialinfantile esotropia.

lowed from infancy until the age of 41⁄2 yearsor older.

As a rule, there is no significant difference inthe angle at near and distance fixation, whichindicates a normal AC/A ratio. The widely heldconcept that essential infantile esotropia is essen-tially nonaccommodative has been challenged bysome authors.50, 244, 245 The ophthalmologist mustbe aware that an accommodative component mayoccasionally be superimposed upon the basic con-dition and require optical correction in case of anuncorrected hypermetropia or bifocals in case ofa high AC/A ratio.

REFRACTIVE ERRORS. Costenbader,54 in a surveyof 500 children with essential infantile esotropia,described the distribution of refractive errors:5.6% myopes, 46.4% mild hyperopes (emmetropiato �2.00D sph), 41.8% moderate hyperopes(�2.25D to �5.00D sph), and 6.4% high hyper-metropes (�5.25D sph, and more). It is of interestin this series of patients that the size of the devia-tion was unrelated to the size and type of refrac-tive error. We have analyzed the refractive errorsin 408 patients with the diagnosis of essentialinfantile esotropia who were treated at our clinicand found a distribution similar to that reportedby Costenbader (Fig. 16–3).

The amount of hypermetropia present at thefirst examination may depend, of course, on theage at which the child is first seen, since numerousstudies have shown that at 1 to 2 years of age


both emmetropia and hypermetropia up to 3D canbe considered as being within normal limits (seeMolnar190 and many others; see also Chapter 7).The generally held view that this ‘‘physiologic’’hypermetropia diminishes as the child grows olderwas challenged by Brown and Kronfeld.31 Theseauthors monitored the refractive error in a groupof children during the first 5 years of life andfound either an increase of hypermetropia or nochange. In a later study, Brown30 reported an in-crease of hypermetropia until the end of the sev-enth year.

Burian34 emphasized that in high hyperme-tropes (�4.00D sph or more) the esodeviation hasa tendency to decrease with passage of time. Infact, 10% to 20% of these patients will eventuallydevelop an exotropia. This observation justifiesconservatism with respect to early surgical treat-ment in such patients (see also (Clark and Noel,46

Moore,191 and Stangler-Zuschrott274).

DUCTIONS AND VERSIONS. Most children withessential infantile esotropia exhibit apparent defec-tive abduction or excessive adduction or both.This is often mistaken for bilateral paresis or pa-ralysis of the lateral rectus muscles. If amblyopiais present, the defective abduction often is moreprominent in the amblyopic eye. If abduction isapparently restricted, one cannot be sure whetherthe child is unwilling or unable to abduct fully.Examination of ocular rotations in extreme posi-tions of gaze is not easy in young infants. Evenolder children and some adults may find it difficultto move the eyes into extreme positions of levo-version or dextroversion. One reason why it maybe difficult to get children with essential infantileesotropia to abduct fully when the fellow eyeis convered is manifest-latent nystagmus. Suchpatients habitually fixate with one eye in adduc-tion, a position in which the nystagmus is leastpronounced or even absent and visual acuity is atits best.

In our experience a true abducens paresis isvery rare in early infancy. The vast majority ofpatients with infantile esotropia and apparentlylimited abduction are either unwilling to abductfully or are unable to do so because of secondarycontracture of the medial rectus muscle(s), con-junctive, or both. In the former condition the doll’shead maneuver or a few hours of occlusion ofeither eye will readily differentiate a true from apseudoparesis of the lateral rectus muscle(s). Inthe latter, a forced duction test may become neces-

sary to diagnose contracture. Recession of thetight medial rectus muscles in such patients willnormalize the action of the seemingly deficientlateral rectus muscle.

The role of the nystagmus blockage syndromein simulating an abducens paralysis is discussedin Chapter 23.

AMBLYOPIA. Amblyopia is a commonly associ-ated factor in essential infantile esotropia. It wasfound in 35% of 408 patients with essential infan-tile esotropia treated in our clinic.205 Costenbader54

reported a prevalence of 41% in his series of500 cases and Shauly and coworkers259 diagnosedamblyopia in 48% of their 103 patients. It isgenerally agreed that amblyopia, unless treatedand cured early in life, is a severe obstacle to thereturn of normal binocular functions. Curiously,the prevalence of amblyopia in patients with es-sential infantile esotropia not operated on is muchlower (14% to 19%).36, 97 The reason for this dif-ference is not clear. However it is unlikely thata large angle esotropia protects a patient fromamblyopia, as proposed by Good and cowork-ers,102 since there is no apparent relationship be-tween amblyopia and the size of the deviation.211

ASSOCIATED VERTICAL DEVIATIONS. To distin-guish clearly between an elevation in adductioncaused by an overacting inferior oblique and adissociated vertical deviation may be difficult ininfants. We suspect that many patients with essen-tial infantile esotropia in whom a diagnosis ofinferior oblique overaction was made in the pastactually had a dissociated vertical deviation. Thedifferential diagnosis between these conditions isdiscussed in Chapter 18. Attention has also beendrawn to the fact that an apparent over- or under-action of an oblique muscle may be simulatedby atopic muscle pulleys45 or by cyclotropia (seeChapter 18). It is for these and other reasons(see Chapter 18) that in recent years we havediscouraged the indiscriminate use of the diagnos-tic label inferior or superior oblique overactionin patients with elevation or depression of theadducting eye and prefer the generic terms ofelevation or ‘‘upshoot’’ in adduction and depres-sion or ‘‘downshoot’’ in adduction instead.

Elevation or depression in adduction, often as-sociated with a V or A pattern, and dissociatedvertical or horizontal deviations are common com-ponents of the essential infantile esotropia syn-drome. We found elevation in adduction in 68%of 408 cases.205 The point is often made that up-

Esodeviations 325

and downshoot in adduction and dissociated devi-ations are infrequently found in children with es-sential infantile esotropia who are under 1 year ofage,122; 229 p.107 and do not emerge until the hori-zontal deviation has been surgically corrected.This has certainly also been our impression. How-ever, it must also be considered that because of thedifficulties encountered in performing a completemotility analysis in infants these conditions arealready present before surgical correction of theesotropia but are not diagnosed because of themasking effect of a large horizontal deviation.Campos38 observed that dissociated vertical devia-tions present before surgery may actually resolveafter early horizontal alignment with chemodener-vation.

The age at surgical correction of the esotropiais unrelated to the occurrence of dissociated verti-cal deviations.122 In fact, this condition occurredalso in 60% of 113 patients with essential infantileesotropia who remained untreated until visualadulthood.36

The prevalence of dissociated vertical devia-tion, which often has a horizontal component (seeChapter 18), in patients with essential infantileesotropia is high. We have diagnosed this condi-tion in 51% of 408 patients with essential infantileesotropia.205 Other authors have reported an evenhigher prevalence, for example, Lang (90%),165

Parks (76%),227 Helveston (70% to 90%),116 andCalcutt and Murray (60%).36 A possible reason forthese differences in the reported prevalence ofdissociated vertical deviations is that some authorsrestrict the diagnosis to the presence of a manifestdissociated deviation whereas others include caseswith a latent dissociated deviation, which can onlybe elicited by covering one eye.

Parks229 believes that a dissociated vertical de-viation is indirect evidence for the onset of esotro-pia at the time of birth. We do not agree with thisview since a dissociated vertical deviation is anentity sui generis. Although it occurs commonlyin association with essential infantile esotropia,this form of deviation also may accompany ac-quired esotropia or exotropia (see Chapter 18).Even patients in whom no other form of strabis-mus is present may have this type of anomaly.Evidence is lacking to support the belief that thepresence of this anomaly is proof of the congenitalnature of an associated horizontal strabismus.

Lang165 commented on the common occurrence(65%) of excyclotropia of the nonfixating eye inhis patients with infantile strabismus. Rather than

considering excyclotropia of the nonfixating eyeas an isolated associated anomaly in the essentialinfantile esotropia syndrome, we prefer to regardit as a component of the dissociated vertical devia-tion syndrome (see Chapter 18).

NYSTAGMUS. The clinical characteristics of thevarious congenital nystagmus forms, including thedifferentiation between manifest-latent and mani-fest nystagmus, are discussed in Chapter 23. Wewill consider nystagmus in this section only as itpertains to essential infantile esotropia.

LATENT OR MANIFEST-LATENT NYSTAG-MUS. These types of congenital nystagmus occurcommonly in essential infantile esotropia and mustbe distinguished from manifest congenital nystag-mus, a less commonly associated oculomotoranomaly. Latent nystagmus is characterized by anasally directed drift of the nonfixating eye, fol-lowed by a fast corrective saccade in the temporaldirection. Upon changing fixation to the felloweye the direction of the nystagmus reverses. Truelatent nystagmus that is present only with one eyeoccluded is rare and in most patients a manifestnystagmus, albeit of lesser amplitude, is presentwith both eyes open; hence the somewhat awk-ward term manifest-latent nystagmus.

We have suggested206 that infanile esotropia,when associated with manifest-latent nystagmus,may well represent a special subgroup within theessential infantile esotropia syndrome. In this con-nection a recent study is of interest according towhich nystagmus when associated with infantileesotropia may increase the risk of requiring addi-tional operations for overcorrection of residualdeviation.271

Since differentiation between manifest-latentand manifest nystagmus is often not possible onclinical grounds alone and reliable electronystag-mographic recordings are difficult to obtain insmall children, both conditions are easily con-fused. This may explain the large differences inthe prevalence of latent nystagmus reported bydifferent authors. For instance, Ciancia42 observedlatent nystagmus that increased in abduction anddecreased in adduction in 33% of patients withessential infantile esotropia, whereas Lang165 madethis diagnosis in 43 (52%) of 82 patients. Electro-nystagmographic studies in a small number ofpatients have even indicated a prevalence of 95%.We have diagnosed nystagmus without the benefitof nystagmographic recordings in only 25% of408 patients with essential infantile esotropia and


were able to recognize the latent variety in only10%.205 As pointed out by Ciancia,42 many ofthese patients have an abnormal head posture andturn their face in the direction of the fixating eye.The nystagmus is less pronounced or even absentin adduction, and improvement of visual acuity inthis position explains the anomalous head posture(see Chapter 23). Spielmann and Spielmann269 em-phasized that this condition is not to be confusedwith the blocking of manifest congenital nystag-mus by convergence.

Earlier studies had led some investigators topropose that a disturbance of coordination be-tween vestibular and optic control of the oculomo-tor system may be of etiologic significance incausing latent nystagmus and dissociated verticaldeviation.80, 81, 165 Doden and Adams81 describedinvoluntary rhythmic, conjugate, pendular devia-tions of the eyes on vestibular testing in 23% of150 strabismic subjects. They interpreted theseanomalies as expressions of a central disturbanceof coordination, possibly caused by lesions of thebrain stem involving the vestibular nuclei and thesubstantia reticularis. Hoyt131 reported abnormali-ties of the vestibulo-ocular response in infantileesotropes without nystagmus. For more recentviews of a causal relationship between manifest-latent nystagmus and optokinetic asymmetry(Kommerell155) and a hypothesis linking latentnystagmus etiologically with infantile esotropia(Lang170), see Chapter 9.

MANIFEST NYSTAGMUS. Most authors reportthat manifest nystagmus occurs less commonlywith essential infantile esotropia than do latentand manifest-latent nystagmus.78, 205, 218 However,it is commonly encountered when essential infan-tile esotropia is associated with other conditions,such as Down syndrome, ocular albinism, cerebralpalsy, and hydrocephalus. Under certain condi-tions patients learn to dampen the nystagmus byconvergence, and this sustained convergence maycause a secondary esotropia (nystagmus blockingsyndrome), which is discussed in Chapter 23. Inthis context it must be underscored that only themechanism of this esotropia is distinctly differentfrom essentially essential infantile esotropia. Otherpatients may dampen the nystagmus in a lateralgaze position.

ASYMMETRICAL OPTOKINETIC NYSTAG-MUS. A common association between optokineticasymmetry and essential infantile esotropia hasbeen established.28, 79, 92, 154, 186, 289, 290 In normalsubjects the optokinetic response elicited by a

rotating nystagmus drum (Fig. 16–4) consists of asmooth pursuit movement in the direction of themoving stripes or pictures, followed by a correc-tive saccade in the opposite direction. This pursuitmovement occurs with equal facility, regardless ofwhether the stripes move from a nasal to a tempo-ral or from a temporal to a nasal direction.

However, in many esotropic patients this sym-metry is grossly disturbed (Fig. 16–5) and pursuitmovements are irregular or are difficult to elicitwhen the drum moves in a nasotemporal direction(optokinetic asymmetry). This phenomenon hasbeen interpreted as a defect in visual motion pro-cessing: the visual cortex fails to acquire the abil-ity to transmit temporally directed object motionto the nucleus of the optic tract (NOT), althoughnot affecting object motion from the retina to thecortex.124, 154 However, this asymmetry is not apathognomonic feature of essential infantile eso-tropia but occurs also in normal, visually imma-ture infants,9, 125 in nonstrabismic patients withdeficient binocular input because of anisometro-pia, and in various other forms of monocular vi-sual deprivation early in life,105, 125, 178 after enucle-ation,246 and in the Duane type I syndrome.105

Its presence is merely evidence for disruption ofbinocular vision during visual immaturity beforethe age of 3 to 4 months, regardless of its cause.Normal and equal binocular visual input is re-quired during infancy for maturation of the optoki-netic reflex and the state of immaturity (asymme-try) persists in the absence of such input. Thus,optokinetic asymmetry must be considered a con-

FIGURE 16–4. Use of a pediatric nystagmus drum toelicit optokinetic nystagmus in children. (Courtesy of Dr.D. Coats, Houston, Texas.)

Esodeviations 327

FIGURE 16–5. Binocular nystagmogram during optokinetic stimulation from nasal to temporal (uppertracings) and temporal to nasal (lower tracings) in a normal subject (left) and a patient with essentialinfantile esotropia (right). Note poor optokinetic response when the drum is moved in a nasotemporaldirection in the esotropic patient. (From Noorden GK von: Current concepts of essential infantileesotropia (Bowman Lecture). Eye 2:343, 1988.)

sequence of essential infantile esotropia ratherthan, as has been suggested,288, 289 the manifesta-tion of a primary motion-processing defect in thevisual pathway. In support of a primary motion-processing defect in these patients it has beenreported that their nonstrabismic first-degree rela-tives demonstrate significant motion-processingasymmetries. However, this finding could not beconfirmed in a study performed by us.88

Westfall and coworkers298 confirmed the exis-tence of asymmetrical optokinetic nystagmus inpatients with essential infantile esotropia. In someof these patients sensory fusion could be detectedby means of dynamic random-dots visual evokedresponse (VER). These authors argued thereforethat optokinetic asymmetry is not associated witha deficit in the cortical fusion facility, but ratherwith deficits in binocular pathways projecting tomonocular optokinetic nystagmus centers. Thesedeficits may be associated with abnormal pro-cessing subsequent to sensory fusion or with ab-normal processing in motion pathways, which runparallel to sensory fusion pathways.

Optokinetic asymmetry is, with certain limita-tions, a useful clinical sign to date the onset ofstrabismus since it occurs more commonly in chil-dren with an onset before the age of 6 months

than in those with a later onset28, 79, 289, 290 (Fig.16–6). Care must be taken, however, in interpre-ting optokinetic responses obtained with a nystag-mus drum in children since the asymmetry maybe subtle and not recognizable unless nystagmog-raphy can be performed.

As mentioned in Chapter 9 the common associ-ation between optokinetic asymmetry and latentnystagmus in essential infantile esotropia has ledto speculations regarding a causal relation-ship.153–156 The reportedly high correlation betweenthe severity of pursuit asymmetry and the intensityof latent nystagmus290 seems to be in accord withthis hypothesis. In further support of it we wouldalso expect an invariable linkage between optoki-netic asymmetry and latent nystagmus. However,latent nystagmus is not consistently associatedwith asymmetry of the optokinetic response79 orwith motion detection deficits.257

MOTION-PROCESSING DEFICITS. The naso-temporal motion defect is not limited to the pursuitsystem and a similar response bias exists for mo-tion processing, as shown by monocularly re-corded VEPs (visual evoked potentials).219, 220 Aswith optokinetic asymmetry this bias is a normalfeature in infants but persists into adulthood in


FIGURE 16–6. Histogram showing the prevalence of clinical monocular optokinetic nystagmus (OKN)asymmetry in esotropic patients with various ages of onset of strabismus. The asterisks indicatestatistically significant differences in prevalence between adjacent columns, and the error barsindicate 95% confidence intervals for mean prevalence. There was a significantly greater prevalenceof asymmetry in esotropic patients with onset before the age of 6 months than in those with onsetbetween 6 and 12 months, and these, in turn, had a significantly greater prevalence than those withlater onset. (From Demer JL, Noorden GK von: Optokinetic asymmetry in esotropia. J PediatrOphthalmol Strabismus 25:286, 1988.)

infantile esotropia. The results of studies on mo-tion perception (reviewed by Fawcett and cowork-ers89) are contradictory with regard to the presenceof a deficit and the direction of monocular asym-metries in infantile esotropia. Kommerell and co-workers157 questioned whether optokinetic asym-metry and motion asymmetries are caused by thesame central defect as they found no significantcorrelation between these disturbances. Fawcettand coworkers89 compared motion perception instereoblind infantile esotropes and patients withacquired esotropia and normal stereopsis andfound similar anomalies in both groups. Theseauthors concluded that interruption of binocularitycannot be the underlying cause of abnormal mo-tion processing in essential infantile esotropia.

ANOMALOUS HEAD POSTURE. Lang165 reportedan anomalous head posture in 57 (70%) of 82patients with essential infantile esotropia, and oth-ers have commented on the high rate of occur-rence of this association.42 The head and face aresaid to be tilted toward the shoulder of the fixatingeye.167 We cannot confirm this high rate of occur-rence, which we have observed in only 6% of 408patients with essential infantile esotropia.205 DeDecker and Dannheim-de Decker73 observed a

conspicuous anomalous head posture in only 2%of their patients and noted a head tilt toward theside of the fixating eye in most instances. How-ever, patients with a head tilt toward the side ofthe nondominant eye often had a dissociated verti-cal deviation with strong unilateral preponderance.In some patients the anomalous head posture isassociated with latent or manifest-latent nystag-mus and the patient turns the head toward the sideof the fixating eye (Ciancia syndrome). However,as pointed out by de Decker71 and in our experi-ence as well, this correlation is by no meansconsistent.

Crone61 has stated that the torticollis compen-sates for an incyclotropia of the fixating eye, aview shared by other authors.4, 266 However, anincycloduction of the fixating eye is not a consis-tent feature of dissociated vertical deviations andone also wonders why a head tilt is not morecommon considering that dissociated vertical devi-ations occur at least in one half of all patientswith essential infantile esotropia.205

The prevalence of various components of theessential infantile esotropia syndrome encounteredin our patient population is summarized in Table16–3.

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TABLE 16–3. Prevalence of Characteristics ofEssential Infantile Esotropia* (N � 408)

Characteristic n Percent

Amblyopia 144 35Anomalous head posture 26 6Dissociated vertical deviation (DVD) 208 51Overaction of inferior obliques (OAIO) 277 68DVD and OAIO (combined) 171 42Manifest nystagmus 62 15Manifest-latent nystagmus 41 10

*Mean deviation at distance, 44� (range,5�–100�); mean devia-tion at near, 49� (range, 10�–95�).

From Noorden GK von: A reassessment of essential infantileesotropia (XLIV) Edward Jackson Memorial Lecture. Am J Oph-thalmol 105:1, 1988.

Therapy

It is a tragic fallacy for parents of strabismicchildren to be told by their family physician thatthe problem will need no medical attention untilthe child reaches preschool age or that in time theeyes will straighten out spontaneously. The truthis that strabismus neglected in early childhoodmay cause severe, irreversible sensory anomaliesand that secondary changes in the extraocularmuscles, conjunctiva, and Tenon’s capsule thatdevelop as a result of long-standing strabismuswill make the results of surgical correction at alater age less predictable. It also behooves theprimary care physician to remember that strabis-mus may develop secondary to reduced visualacuity and may well be the second most commonsign of retinoblastoma.86

We insist therefore that every child whose eyesare not aligned by 3 months of age be given acomplete ophthalmologic examination. Althoughtreatment may not be possible or even necessaryon the first visit, a baseline of clinical informationcan be established that will be helpful in the futuremanagement of the patient.

The treatment of choice for essential infantileesotropia is surgical alignment of the eyes. Non-surgical treatment is directed toward correctionof a significant refractive error, elimination ofamblyopia during the preoperative phase, andtreatment of a residual angle of esotropia duringthe postoperative period.

GOALS OF TREATMENT. A cure of strabismusmay be defined as a restoration of single binocularvision in the practical field of gaze, that is, ortho-tropia or asymptomatic heterophoria; normal vi-sual acuity in each eye; normal stereoacuity on

random-dot testing; normal retinal correspon-dence; and stable sensory (bifoveal) and motorfusion. The isolated case of Parks230 in whichbifixation was restored, and the cases of Wrightand coworkers303 in which normal random-dot ste-reopsis was achieved notwithstanding, there isuniversal agreement among strabismologists thatcomplete restoration of normal binocular visionwith normal random-dot stereopsis is unattainablein essential infantile esotropia except in the rarestof circumstances. However, this conclusion neednot lead to capitulation before a seemingly incur-able anomaly in which surgery produces at best animproved cosmetic appearance. Stereopsis, whileessential for a certain, though limited number ofoccupations, is not indispensable in the presenceof monocular clues for depth perception. More-over, stable sensory and motor fusion may occurin the absence of stereopsis.

A cure is not absolute, but consists of severalgrades of subnormal or abnormal binocular vision.We must ask: What is the nature of these lessthan ideal forms of binocular vision? Of whatfunctional benefit are they for the patient? Howoften do they occur in a group of surgically treatedpatients with essential infantile esotropia? Doestheir occurrence depend on the age at which theeyes are surgically aligned?

NONSURGICAL TREATMENT. We stated in thebeginning of this chapter that hypermetropic re-fractive errors not exceeding 2D to 3D are physio-logic variants in infants. The question arises withrespect to essential infantile esotropia whether cor-rection of a small hypermetropic refractive erroris indicated. Essential infantile esotropia generallyis nonaccommodative; that is, the AC/A ratio isusually normal, high hypermetropic refractive er-rors are rare (see Table 16–3), and little if anydifference exists between the angle of deviationmeasured at distance and near fixation. However,as mentioned earlier, exceptions do occur, andrefractive and nonrefractive accommodative eso-tropia can have their onset in early infancy.

We have observed on occasion a high AC/Aratio in patients with essential infantile esotropiawithout a refractive error. In such cases, the eso-tropia increases significantly at near fixation andlittle if any deviation is present at distance fixa-tion. Before this diagnosis can be established ininfants, one must, of course, rule out interferencewith steady fixation at distance through lack ofattention during the measurement.


It has become our policy to correct all hyper-metropic refractive errors in excess of �2.50Dsph before considering surgery. In uncooperativeinfants, a trial of miotics may be considered inlieu of glasses. In most patients with essentialinfantile esotropia, however, correction of the‘‘physiologic’’ low-degree hypermetropia has lit-tle, if any, effect on the deviation.

The view that essential infantile esotropia inmost instances is nonaccommodative was chal-lenged by Rethy and Gal,245 Rethy,244 and Ket-tesy.150 These authors rejected the concept of con-genital nonaccommodative esotropia and claimedthat in a high percentage of cases the deviation isaccommodative in origin. Rethy noted that aftercorrection of the full hypermetropic refractive er-ror in esotropic children and repetition ofcycloplegic refraction a month or two later, reti-noscopy revealed a higher refractive error thanwas found on the first examination. After increas-ing the prescription and overcorrecting the hyper-metropia by 0.5D to 1.0D, he noted reduction ofthe angle of deviation. Such patients were atropi-nized to facilitate acceptance of the overcorrec-tion. When the procedure was repeated severaltimes, latent hypermetropia became increasinglymanifest and was corrected or overcorrected untilthe accommodative effort was decreased to thepoint where the associated accommodative con-vergence no longer caused esotropia. Rethyclaimed that unless this therapy is instituted inearly infancy, the increased accommodative tonusand the associated increased accommodative con-vergence will stabilize and become refractory tobelated therapeutic measures. According to thisauthor, such cases are then erroneously referredto by strabismologists as ‘‘nonaccommodative.’’Rethy claimed that surgery can be avoided in90% [sic] of esotropic patients if his method oftreatment is followed.244

We are in full agreement with Rethy and Ket-tesy concerning the validity of Donders’ theorywhenever it is applicable. We also stress the oftenneglected need for full correction of a hypermetro-pic refractive error and for frequent refractions inpatients with accommodative esotropia, in view ofthe findings of Brown and Kronfeld31 and those ofBrown.30 Furthermore, the effectiveness of atropi-nization in causing complete cycloplegia varies indifferent patients, and latent hypermetropia mayinitially go undetected66 and become only gradu-ally manifest as corrective lenses are worn forsome time. On the other hand, the angle of devia-

tion in essential infantile esotropia as a rule isnot consistent with the excess of accommodationrequired to overcome hypermetropia. In most in-stances there is no relationship between the angleof strabismus and the size or type of refractiveerror in essential infantile esotropia.54 The devia-tion usually is considerably greater than it wouldbe if the excess convergence were related to theincreased accommodative effort. Moreover, a pro-spective study by Ingram and coworkers140 hasshown that a prophylactic correction of hyperme-tropic refractive errors in excess of 2.00D didnot prevent development of strabismus. Thus theextension of Donders’ doctrine by Rethy and Ket-tesy to include the vast majority of patients withessential infantile esotropia is not justified in ouropinion, which should not detract from the factthat the theory of Donders remains the best sub-stantiated explanation for accommodative strabis-mus (see Chapter 9).

Amblyopia should be treated rigorously beforeand not, as advocated by some authors,162, 294 aftersurgery for the following reasons: (1) The earlierin life the treatment is begun, the shorter theduration of treatment. (2) The diagnosis of ambly-opia and the monitoring of the fixation preferenceduring treatment are more difficult once the eyesare aligned or nearly aligned by surgery than inthe presence of a large angle esodeviation.37, 207 (3)Once the eyes are aligned some parents may belulled into thinking that all problems are overand become negligent in keeping their follow-upappointments. We have repeatedly seen childrenwith deep amblyopia who had early surgery andwho, in spite of our instructions, did not return toour office until years later. (4) The outcome ofsurgery is less favorable in patients who remainamblyopic at the time of surgery.148, 258, 259 Thetime for surgery has come when the child alter-nates freely or can hold fixation with the formerlyamblyopic eye through a blink.

Some investigators have recommended the useof prisms in the preoperative treatment of essentialinfantile esotropia.77, 292 However, this treatmenthas never become popular and is not used by us.Prismatic therapy and the prism adaptation testare discussed in Chapter 24.

SURGICAL TREATMENT

TIMING OF SURGERY AND RESULTS. Muchdiscussion has centered on the optimal time atwhich to operate on children with essential infan-tile esotropia. Several schools of thought have

Esodeviations 331

evolved, some advocating surgery as early as 3months and others as late as 4 years of age. Fiftyyears ago an operation at 4 or 5 years of age wasconsidered early and in most instances surgerywas not contemplated until the child was readyfor school. There has been a general tendencyamong ophthalmologists to operate on childrenyounger than was customary then. Improvedsafety of anesthetic procedures has reduced thesurgical risk to an almost negligible minimum. Asteadily growing group of surgeons now believethat an operation for essential infantile esotropiais advisable before completion of the first 24months of life and some prefer to complete sur-gery during the first 12 months or even earlier.25,

53, 136, 138, 277, 279–282, 303, 305 The arguments for thisreasoning are that early surgical treatment pro-vides a better chance for functional improvement,is desirable for psychological reasons, and thatsecondary changes occur in the extraocular mus-cles, the conjunctiva, and Tenon’s capsule—all ofwhich make a correction at a later date moredifficult and less predictable.

Early surgery was pioneered by the late FrankCostenbader who in 1958 stated:

I feel strongly that we should, first, regain and maintainvision in each eye from early childhood, and, second,regain binocular alignment as early in infancy andchildhood as possible and to maintain it thereafter.53, p. 331

Costenbader’s plea for early surgical alignmentof the eyes was undoubtedly influenced by Cha-vasse,40, p.519 who, in turn, was influenced by thePavlovian thinking of his time. Chavasse statedthat the opportunity for early single binocular vi-sion is of paramount importance for developmentof normal binocular reflexes. Sporadic reports inthe literature of normal or near-normal random-dot stereopsis after surgical alignment before 6months of age seemed to support this view.53, 138, 303

Other eye surgeons advocated operating whenthe child is about 2 years of age6, 16, 72, 180 oreven older.10, 134, 146, 179 Many clinicians believethat examination during early infancy cannot besufficiently complete for careful surgical planning;that associated vertical anomalies, including the Aand V patterns, overaction of the inferior obliquemuscles, or dissociated vertical deviations maybe overlooked; and that the deviation at distancefixation cannot be evaluated reliably before 2years of age.

The older literature is replete with a pessimisticoutlook regarding the functional outcome follow-

ing surgery in patients with infantile strabismusthat is based on Worth’s assumption that a congen-ital defect of the fusion faculty is the cause ofsquint.301 Indeed, the view was common that nor-mal binocular functions are obtained rarely, ifever, when the deviation dates from birth.18, 174, 175

The beneficial effect of surgical alignment ofthe eyes by the age of 24 months was first dis-cussed in the frequently quoted paper by Ing.136

Other studies6 came to the same conclusion. Themajor problem in evaluating much of this workinvolves the interpretation of tests used to deter-mine the presence of binocularity. We find it erro-neous to assume, as is frequently done,57, 139, 277, 280,

305 that gross stereopsis, a positive Worth four-dottest, or visibility of the two stripes during theBagolini striated glasses test are indicators of fu-sion when in fact any or all of these responsescan be elicited when a manifest residual esodevia-tion is present along with anomalous retinal corre-spondence.202, 203 The binocular cooperation on thebasis of anomalous retinal correspondence be-tween the fovea of the fixating eye and a periph-eral retinal area in the eye with a residual eso- orexodeviation is functionally not equivalent to sta-ble normal binocular vision at all fixation dis-tances with fusional amplitudes! Unless a cleardistinction is made between normal and anoma-lous binocular vision in evaluating the results ofpatients operated on and aligned at different ages,no conclusions regarding the therapeutic superior-ity of operating at an early age can be drawn.

A second problem with many studies on theresults of surgery in essential infantile esotropia isthat contemporary authors, too numerous to citehere, consider a residual deviation of 10� a satis-factory surgical outcome. Must it be emphasizedthat orthotropia, eso- and exophoria, intermittentheterophoria, and eso- and exotropias of 10� arefunctionally not the same? If no distinction ismade on the basis of the cover and the cover-uncover tests that this residual deviation is a het-erophoria or a heterotropia at all fixation distances,the criterion of 10� for surgical success is mis-leading and therefore useless. At best, it tellswhether the patient has been cosmetically im-proved by the surgery.

A third problem with many of the older studiesis that no distinction is made between the age atthe first operation and the age at which alignmentwas accomplished. Clearly, only the latter is rele-vant to this discussion.


In an effort to improve communication betweenclinical investigators and with the shortcomings,mentioned above, of previously used outcome cri-teria in mind, we suggested the following classifi-cation of the results of surgery in essential infan-tile esotropia:(1) subnormal binocular vision, (2)microtropia, (3) small angle esotropia or exotro-pia, and (4) large angle esotropia or exotropia.205

Some of the clinical features of these conditionsare summarized in Table 16–4, and the tests em-ployed for their diagnosis have been discussed inChapter 12 (see also von Noorden203). Table 16–4has been modified from previous editions in re-sponse to questions raised regarding its clarity.250

We consider subnormal binocular vision, aterm introduced by Lyle and Foley181 and alsoused by de Decker and Haase,74 as an optimaltreatment outcome and have never seen a resultbetter than that in infantile esotropia. Unlike inmicrotropia, the patient fixates centrally, has nor-mal visual acuity in each eye, and behaves in allother respects like someone with normal binocularvision, except for reduced stereopsis and a fovealsuppression scotoma in one eye that is only pres-ent under binocular conditions. As will be dis-cussed later in this chapter, microtropes are oftenmildly amblyopic with parafoveolar fixation andhave anomalous retinal correspondence with iden-tity of the angle of anomaly and the degree offixation excentricity. Microtropes with foveolarfixation in each eye may be difficult to distinguishfrom patients with subnormal binocular vision andwe readily admit that this is a transitional zonein the classification of outcomes presented here.Clearly, however, a microtropia because of the

TABLE 16–4. Classification of Surgical Outcomes in Essential Infantile Esotropia

Subnormal Binocular Small Angle ET/XT Large Angle ET/XTVision Microtropia (<20�) (>20�)

Orthotropia or asymptomatic Inconspicuous shift or Appearance improved; most Conspicuous residualheterophoria no shift on cover test parents are happy with angle

outcomeNormal VA in each eye Mild amblyopia is Amblyopia may be present

commonNRC Usually ARC ARC is common ARC or suppression

Fusion with amplitudes Anomalous fusion on the basis of ARC No fusion

Reduced stereopsis Stereopsis reduced or absent Absence of stereopsis

Stable alignment Some stability Less stability May be unstable

No further treatment No treatment except for amblyopia Additional surgery may berequired

Optimal outcome Less than optimal but still acceptable Unacceptable outcome

ARC, abnormal retinal correspondence; ET, esotropia; NRC, normal retinal correspondence; VA, visual acuity; XT, exotropia.

amblyopia is less advantageous from a functionalpoint of view than is subnormal binocular visionand must therefore be considered a less than opti-mal but acceptable outcome.

Subnormal binocular vision and microtropia areoften thought of as favoring motor stability, thatis, being protective against a recurrence of strabis-mus. However, several studies have shown thatwhereas the stability of alignment is significantlybetter when these conditions are present as op-posed to when they are not, deterioration doesoccur.7, 123, 291 Residual small angle eso- or exotro-pias of less than 20� do not interfere with thenormal appearance in most patients and in thiscase require no further treatment, except for a stillexisting or recurrent amblyopia. As in microtropiawe speak of a less than optimal but still acceptableoutcome when a residual but small deviation re-mains. Residual esotropia or consecutive exotropiarequiring surgery is clearly an unacceptable out-come.

Using these criteria we have analyzed resultsof surgical attempts to align the eyes to an ortho-tropic position as closely as possible by one ormultiple operations in 358 patients with a docu-mented onset of esotropia before the age of 6months.205 Figure 16–7 lists the prevalence of thevarious functional endstages of therapy accordingto whether surgical treatment was completed be-tween 4 months and 2 years, 2 to 4 years, or olderthan 4 years after a mean follow-up of 39 months.This analysis shows that as age at completion ofsurgical therapy increases, the probability of anoptimal outcome (subnormal binocular vision) de-creases. Increasing age at the completion of treat-

Esodeviations 333

FIGURE 16–7. Prevalence of functional state in 358 patients according to age at alignment. SBV,subnormal binocular vision; ET, esotropia; XT, exotropia. (From Noorden GK von: A reassessment ofessential infantile esotropia (XLIV Edward Jackson Memorial Lecture). Am J Ophthalmol 105:1, 1988.)

ment tends to move the patient away from subnor-mal binocular vision and into the functionallyinferior microtropia and small angle esotropia orexotropia group. These data, although based onevaluation criteria quite different from those usedby previous investigators, are in support of thecurrent view that surgery completed before theage of 2 years yields superior results. They havebeen confirmed by Shauly and coworkers259 whohave adopted our classification of surgical results.However, they are at variance with the admonitionthat unless surgery is completed before that time,a functionally useful form of binocular vision can-not be expected.281 In fact, many of our patientsachieved such results when surgical treatment wasconcluded after the age of 2 or even 4 years. DeDecker has confirmed these findings.72

Although these results are far from perfect,they are not nearly as dismal as one must concludefrom the older literature,18, 174, 175, 301 especiallysince we have learned to consider anomalous cor-respondence in a more favorable light (see Chap-ter 13). Some form of binocular cooperation rang-ing from near-normal (subnormal binocularvision) to anomalous (microtropia and small angleesotropia or exotropia) existed in 66% of ourpatients. To the mother who asks, ‘‘Is this opera-tion done for cosmetic reasons or will my childever learn to use the eyes together?,’’ we cananswer, ‘‘There is an above-average chance forsome form of binocular cooperation after surgery,

although normal depth perception cannot be ex-pected.’’

Until such time that new information becomesavailable that may require modification of thisapproach we advocate surgery when the followingcriteria are met: (1) demonstration of a stableand sufficiently large deviation, (2) absence ofan accommodative factor, (3) alternating fixationbehavior after treatment of amblyopia, and (4)identification of the nature of associated verticaldeviations or of vertical incomitance (A or V pat-terns). As soon as this information is unequivo-cally available, we see no reason to delay surgery.In addition to functional and psychological bene-fits (see Chapter 10) there is some evidence thatthe child’s motor development improves after sur-gery.249 Although controlled studies are needed tovalidate this point, it is certainly astonishing, andperhaps more than just a coincidence, how oftenparents will report spontaneously during postoper-ative visits that the child stumbles and runs intowalls less often. In this connection it may be ofinterest that expansion of the binocular field ofvision has been reported in adults after surgeryfor esotropia.159, 302

The completeness with which all necessary pre-operative information can be obtained dependslargely on the cooperation of the child as well asthe patience and understanding of the examiner.In some patients, these data can be obtained by 6months of age or earlier,55 whereas in others the


surgeon may be forced to procrastinate until thechild is 2 years of age or older.

Of special significance with regard to outcomeexpectations is the fact that normal stereoacuityremains such an elusive therapeutic goal in theoverwhelming majority of patients with essentialinfantile esotropia. In view of the extraordinarysensitivity to conflicting visual input of corticalbinocular neurons mediating stereopsis in infantkittens132 or infant monkeys,58–60 the question arosewhether surgery even at the age of 6 months maybe too late to preserve stereopsis. Several recentstudies have addressed this point and the resultsare controversial. Birch and coworkers25 reportedbetter random-dot stereopsis in children operatedupon between the ages of 5 and 12 months thanin another group who had surgery at 13 to 18months. Wright and coworkers303 operated onseven patients between the ages of 13 and 19weeks and achieved normal stereopsis (Titmustest) in two cases. However, Ing138 examined 16patients who were surgically aligned by other oph-thalmologists at a mean age of 4.2 months butwas able to identify only one patient with refinedstereoacuity of 40 seconds of arc (Titmus test)and 20 seconds of arc (Randot test). Likewise,Helveston and coworkers122 who operated on 10patients aged 4 months found stereopsis of 140seconds (Titmus) in only one instance.

We do not believe that the evidence thus farpresented in favor of operating before the age of6 months is sufficient to advocate this approachon a general basis. Long-term follow up studiesare essential to improve our knowledge as to thefunctional benefits to be derived from operatingthat early in life. The longitudinal study of patientsthus treated by Helveston and coworkers122

showed subsequent deterioration after initial ocu-lar alignment in many instances.

The observations that normal or near-normalstereopsis can be restored at all in isolated in-stances after surgical alignment before the age of6 months is of interest with regard to the etiologyof infantile esotropia. Stereopsis has been demon-strated by objective means, at least transiently,in esotropic infants corrected with prisms189 orimmediately after surgical alignment and before aresidual strabismus established itself.5, 248 On theother hand, we have learned that artificial strabis-mus produced in infant monkeys for as briefly as1 week decimates the number of striate neuronsthat normally receive input from both eyes12, 58 and

that are linked to stereopsis.15, 59, 60 This loss ofbinocular neurons is irreversible in monkeys evenafter realignment of the eyes and subsequent expo-sure to a normal visual environment for as longas 2 years. In view of the great functional andanatomical similarity of the visual system in mon-keys and humans it is reasonable to conclude thatdefective stereopsis in infantile esotropes, similarto optokinetic asymmetry, is an irreversible conse-quence of strabismus early in infancy rather than,as has been stated, the manifestation of a geneticsensory defect232 in the afferent visual pathwaythat precludes complete functional recovery.

Presuming that the sensory substrate before on-set of the esotropia was normal, we must ask whyonly such a small number of patients recovernormal or near-normal stereopsis in spite of veryearly surgery? Among the possibilities to be con-sidered are that surgery as early as 3 to 4 monthswas already too late and that the destruction ofcortical binocularity had already occurred beforealignment was accomplished. The minimal dura-tion of incongruous visual stimulation necessaryto permanently impair cortical binocular cells isunknown in humans, and interindividual differ-ences in susceptibility may well exist. Second, thedegree of functional recovery may depend on theduration of a brief period of normal binocularvisual input or of intermittency of the deviationprior to the onset of constant esotropia. We knowthat essential infantile esotropia has its onset usu-ally during the first 3 months of life and is rarely,if ever, present at birth (see p. 321). Thus, abrief period or, in the case of early intermittency,periods of normal binocular stimulation may wellhave been present prior to the onset of esotropiaand stabilized binocular connections to the pointwhere they may be recoverable after alignment.Third, a residual angle of esotropia after surgerymay preclude normal stereopsis.

In addition to defective stereopsis, a secondand perhaps etiologically related residual sensorydefect persists even in patients with optimal ordesirable surgical outcome. This consists of a fo-veal suppression scotoma in one eye of a patientwith subnormal binocular vision and microstrabis-mus. This scotoma, to which Parks226 and vonNoorden and coworkers216 drew attention, meas-ures 2� or less in diameter and may be presentonly under binocular conditions of seeing. It usu-ally occurs in the nondominant eye but may switchrapidly from one eye to the other (alternating

Esodeviations 335

foveal suppression). The scotoma is diagnosedwith the 4� base-out prism test (see p. 218) or bya decrease of visual acuity in one eye when acuityis determined under binocular conditions of seeingwith a polarized projected chart.204 Thus postoper-ative alignment in patients with essential infantileesotropia is maintained by peripheral fusion aloneand is not dependent on normal bifoveal interac-tion. Few will disagree that this state of binocularcooperation, although not perfect, is of functionalbenefit to the patient.

Although an etiologic and pathophysiologic re-lationship may exist between a binocular fovealsuppression scotoma and reduced stereoacuity, touse the degree of stereoacuity as an indicator forsuppression of bifoveal fusion, as proposed byParks,226 is not justified. Normal stereoacuity (15to 60 seconds of arc on any of the random-dotstereograms) is indisputably the hallmark of nor-mal binocular function. On the other hand, subnor-mal stereoacuity or even stereoblindness can bepresent in orthotropic subjects with stable fusion.The mere reduction of stereoacuity alone is insuf-ficient proof of foveal suppression.

In summarizing the ongoing discussion as tothe optimal age at which to operate, it is fair tostate this has yet to be established. Normal stere-opsis has been restored only in isolated cases aftersurgical alignment prior to the sixth month of life.There is evidence from many independent studiesthat surgery completed before the second year oflife improves the chances for recovery of limitedbinocularity. However, it has also been shown thatsuch recovery may occur if surgery is delayed upto or beyond the age of 4 years. Strabismologistsare awaiting eagerly the outcomes of two ongoingprospective multicenter trials in the United Statesand in Europe188, 284 that address this important is-sue.

TYPE OF OPERATION. Our surgical approachto treatment of essential infantile esotropia hasundergone periodic changes over the years. Ini-tially, we favored a recession-resection operationon the nondominant eye, combined with inferioroblique myectomies, if indicated, to be followed,if necessary, by a recession-resection on the felloweye. The amount of surgery varied according tothe size of the deviation and on the basis ofobservations made during examination of the duc-tions of the eyes and ranged from 3- to 5-mmrecessions and 5- to 8-mm resections.216 However,the number of reoperations required to gain or

maintain alignment was discouraging. In 1972 wereported that an average of 2.1 operations perpatient was required to align the eyes.216 Ing andcoworkers,139 who used 3- to 5-mm recessions ofboth medial recti, required as many as 2.6 opera-tions per patient to achieve this goal. In recentyears we have changed our method and now em-ploy recessions of the medial recti ranging from 5to 8 mm, provided the deviation measures 30�

or more at near fixation.239 This more aggressiveapproach has decreased the need for additionalsurgery and, contrary to our initial concern, doesnot cause limitation of adduction. Initial reportsshow that by doing these unconventionally largerecessions of both medial recti, 73% to 84% ofthe patients are successfully aligned with one op-eration.121, 160, 240, 295 In the presence of a signifi-cantly large residual deviation, we resect bothlateral rectus muscles in a second procedure. Ithas been advocated that the conventional amountof surgery in myopia be increased because of ahigher percentage of unacceptable undercorrec-tions.258

At this time we use a unilateral recession-resection operation on the nondominant eye infre-quently to treat essential infantile esotropia andonly in patients who have failed to respond toamblyopia treatment.

The use of posterior fixation sutures in lieuof large bimedial recessions of the medial rectusmuscles in the treatment of essential infantile eso-tropia is enjoying greater popularity in Europe,especially in Germany, than elsewhere. This ap-proach is preferred by some because it is said toreduce the prevalence of consecutive exotropia.Seventy-five percent of patients thus operated onachieve an alignment between 2� exodeviation and10� esodeviation,70, 107, 147 which is comparable towhat can be accomplished with large recession ofboth medial rectus muscles (see above).

POSTOPERATIVE TREATMENT

Postoperative care should be concerned primarilywith the prevention of strabismic amblyopia (seeChapter 24) and correction of a hypermetropicrefractive error.13 Since most postoperative pa-tients have a small angle esotropia and a deep-seated anomalous retinal correspondence, subjec-tive complaints about diplopia or other types ofvisual discomfort are practically never encoun-tered. Although from time to time the suggestionhas been made, with varying degrees of enthusi-


asm, that such patients should be treated orthopti-cally, we have not found this treatment of muchvalue (see Chapter 24).

CHEMODENERVATION

Injection of the extraocular muscles with botuli-num toxin, type A (Botox) has been suggested asa viable alternative in the treatment of infantileesotropia. For further discussion, see Chapter 25.

Nonaccommodative ConvergenceExcess Esotropia (Normal AC/ARatio)

Definition

Nonaccommodative convergence excess esotropiais defined as an esotropia that is larger at near (atleast 15�) than at distance fixation in an opticallyfully corrected patient whose AC/A ratio is normalwhen determined with the gradient method.208


As is the case in accommodative esotropia, theonset is early in life, occurring as a rule between2 and 3 years of age, but we have also seenpatients in whom the onset was shortly after birth.Such patients are characteristically orthotropic orhave a small angle esotropia at distance fixationand a larger esotropia (20� to 40�) at near fixation.In contradistinction to esotropia with a highAC/A ratio, however, relaxation of accommoda-tion by bifocals or its facilitation by miotics haslittle if any effect on the near deviation. TheAC/A ratio, if determined with the gradientmethod, may be normal or abnormally low.208 Thiscondition differs from the ‘‘hypoaccommodative’’esotropia of Costenbader53 (see above) inasmuchas the near point of accommodation is within thenormal range. Obviously, excessive convergencein such patients must occur on a basis other thanaccommodation, perhaps from tonic innervation,which is the reason we suggested the term nonac-commodative convergence excess for this entity.208

Clearly, an abnormal distance-near relationship inthe angle of esotropia is not always caused, as hasbeen assumed,229, p.60 by a high AC/A ratio. Thewidespread and, in our opinion, unsound practiceof determining the AC/A ratio by comparing thedistance and near deviation (heterophoria method;see Chapter 5) is likely to miss the diagnosisof nonaccommodative convergence excess and to

subject such patients to bifocal therapy to whichthey will not respond.187, 208. Case 16–4 illustratesthe features of this form of esotropia.

CASE 16–4

A 51⁄2-year-old girl was first noted to intermittentlycross her eyes when she was 2 years of age. Ambly-opia of OD was diagnosed by her local ophthalmolo-gist, and she responded well to occlusion treatmentbegun at 4 years of age. On examination, her uncor-rected visual acuity was 20/40 � 1 OD and 20/25� 2 OS. The prism and cover test showed 12�

esotropia at distance and 30� at near. When themeasurement was repeated on several occasionswith the patient looking through �3.00 sphericallenses, the near deviation still measured 22�. Thepatient manifested a slight A pattern with minimaloveraction of both superior oblique muscles.Cycloplegic refraction indicated the presence of mildhypermetropia of �0.75 sph OD and �1.00 sphOS. The remainder of the examination, includingthe fundus examination, was normal. Clearly, thepersistent increased near deviation after relaxationof accommodation with �3.00 spherical lensesmust have been caused by factors other than ac-commodative convergence.

Treatment

Since bifocals or miotics are ineffective in control-ling the deviation at near, surgery must be consid-ered for the nonaccommodative element of theanomaly. In our hands, a conventional recessionprocedure of both medial rectus muscles (4 to 5mm) alone or combined with posterior fixationsutures has been surprisingly ineffective in sig-nificantly reducing the near deviation. In fact, thiscombined operation performed in the patient de-scribed in Case 16–4 reduced the near deviationfrom 30� to 25� esotropia! We feel that unconven-tionally large recessions of both medial rectusmuscles (5 to 8 mm) may be more effective,but more clinical experience must be accumulatedbefore recommendations regarding the most effec-tive management can be made.

Acquired or Basic Esotropia

Definition

We define acquired nonaccommodative esotropiaas a comitant esotropia with a gradual onset after6 months of age but usually limited to childhoodand a near deviation that approximately equals the

Esodeviations 337

distance deviation. Unlike in refractive accommo-dative esotropia a significant uncorrected hyper-metropic refractive error is absent and unlike innonrefractive accommodative esotropia the AC/Aratio is normal.


Costenbader53 referred to this type of deviation as‘‘acquired tonic esotropia,’’ and the Hugonnierscalled it ‘‘essential esotropia of late onset.’’134, p. 210

At the onset the angle of strabismus generally issmaller than in patients with essential infantileesotropia, but the angle tends to increase to amagnitude of 30� to 70�. Since the eyes usuallystraighten out or even become divergent undergeneral anesthesia and since the forced ductiontests are, as a rule, negative, we are inclined toimplicate an innervational anomaly rather thanmechanical factors as the cause of this form ofstrabismus. Because parents frequently associateonset of the deviation with injury, illness, or emo-tional upset of the child, Costenbader53 postulatedthat such patients have an excessive convergencetonus that is controlled initially by fusional diver-gence but is disrupted easily by exogenous factors.

The clinician should always keep in mind thepossibility of an underlying lesion or malforma-tion in the central nervous system in a youngpatient with acquired nonaccommodative esotro-pia, the onset of which need not always be acute.3,

8, 26, 171, 235, 293, 299 Many of these patients receivetreatment for their esotropia and some even un-dergo strabismus surgery3, 171, 304 before the correctdiagnosis, which may include a brain tumor orother life-threatening condition, is made. It be-hooves the ophthalmologist to search for signs ofincreased intracranial pressure in all patients withan acquired esotropia.171 Special vigilance is calledfor when the esodeviation is greater at distancethan at near fixation (divergence paralysis; seeChapter 22), which has been described in a tumorof the corpus callosum3 and in Arnold-Chiari mal-formation.26, 235

The importance of a fundus examination to ruleout papilledema or optic atrophy in every patientwith strabismus is convincingly demonstrated bythe case report of a patient with a gradually ac-quired esotropia who turned out to have an under-lying life-threatening condition.

CASE 16–5

A 5-year-old boy who had gradually developed eso-tropia 6 months before our seeing him was referredfor treatment of amblyopia. The referring physicianhad performed a cycloplegic refraction (�3.50 sphOU) and prescribed glasses. On examination, thebest corrected visual acuity was 6/30 OD and 6/9OS. The prism cover test showed a comitant esotro-pia of 40� at distance and 50� at near fixation. Exami-nation of the ductions and versions revealed minimalunderaction of the right lateral rectus muscle andminimal overaction of the right superior oblique mus-cle. The patient suppressed OD at near and distancewith the Worth four-dot test. Fundus examinationshowed massive choking of the optic nerve head inboth eyes. Computed tomography revealed a mid-line posterior fossa tumor, which was successfullyremoved 2 days later and identified as an astrocy-toma. The papilledema receded postoperatively, andvisual acuity OD improved to 6/9 after 1 month ofocclusion therapy. The esotropia remained un-changed, however, and 4 months after brain surgerythe right medial rectus muscle was recessed 4 mmand the right lateral rectus muscle resected 7 mm.Six months after muscle surgery the patient had abest corrected visual acuity of 6/9 OD and 6/6 OS.The patient was orthophoric at near and distancefixation, and he had 60 seconds of arc stereoacuitywhile wearing his glasses. Without glasses he hada residual esotropia of 4� at distance and 10� at nearfixation. Fundus examination revealed postpapilliticgliosis but no atrophic discoloration of the nerveheads.

Therapy

Therapy consisting of elimination of amblyopiafollowed by surgical correction should be startedas soon as possible after the onset of the deviation.Since a period of normal binocular vision hasexisted for at least 6 months or longer before theonset of the disease, the prognosis for normaliza-tion of binocular functions is better than in thosewith essential infantile esotropia, provided treat-ment is started without delay. Lang171 reported thatif onset occurs after the age of 11⁄2 years a com-plete cure as defined by orthotropia and random-dot stereopsis becomes possible after surgicalalignment and he referred to this form of strabis-mus as normosensorial late-onset esotropia.Dankner and coworkers67 reported that a consecu-tive exotropia in these patients during the immedi-ate postoperative period resulted in a higher inci-dence of fusion than in those who were initiallyorthophoric or undercorrected.


Esotropia in Myopia

It is well established that myopia is present in3% to 5% of patients with nonaccommodativeesotropia, and most clinical characteristics of thisesotropia are no different from those associatedwith emmetropia or hypermetropia. There are,however, two special forms of esotropia occurringwith myopia that, in view of their unusual fea-tures, deserve separate discussion. Von Graefe103

recognized the first type, and Bielschowsky20 laterdescribed it in detail. The esotropia is accompa-nied by diplopia first only at distance and eventu-ally also at near fixation, mild limitation of abduc-tion in both eyes, and normal adduction. It occurspredominantly in young myopic adults. The expla-nation given by von Graefe and Bielschowsky forthe etiology of this entity is speculative.Bielschowsky advised resection and advancementof both lateral rectus muscles to treat these pa-tients. This condition must be very rare since wehave encountered it only once in 35 years of apractice, in a 19-year-old Asian man who had amyopia of �6D in both eyes.

The second type is caused by restrictive factorsand will be discussed in Chapter 21.

The treatment of unrestrictive esotropia withmyopia is not different from the treatment of hy-permetropic esotropes. However, special precau-tions are in order in a patient with a thin sclera.To avoid any scleral suturing we have successfullytreated a highly myopic esotropic patient witha history of retinal detachment by performing amarginal myotomy of the medial rectus and aresection followed by end-to-end suturing of thelateral rectus muscle.201 Coats and Paysse48 re-ported a technical modificiation of the classic re-cession and resection procedure to avoid scleralsutures in such cases.

Acute Acquired Comitant Esotropia

The onset of acute acquired comitant strabismusis always an alarming event for both the patientand the physician. In young children and infantsthe acute mode of onset can rarely be determinedwith certainty and voluntary closure of one eyemay often be the only sign. In older children oradults with acute strabismus, sudden diplopia isof immediate concern and the onset of the diseaseoften can be traced to a precise hour of a particularday. In patients with acute strabismus, regardlessof how obvious the etiology might be, an espe-

cially careful motility analysis is always necessaryto rule out a paretic deviation.

Unilateral or bilateral paresis of the abducensnerve, commonly the first manifestation of a cen-tral nervous system disorder or of a medical prob-lem, may cause an acute esotropia with an anglegreater at distance than at near fixation (see alsodivergence paralysis, Chapter 22). This deviationmay quickly become comitant, in which case itwill be difficult to recognize the paretic element.Thus any acute esotropia with the prominent com-plaint of diplopia of sudden onset calls for in-creased vigilance and may require a neurologicevaluation even though its cause may be quiteharmless.

We distinguish three forms of acute comitantstrabismus: (1) that occurring after artificial inter-ruption of binocular vision; (2) that occurringwithout interruption of binocular vision as a resultof a decompensated esophoria; and (3) that causedby an intracranial pathologic process.

Acute Strabismus After ArtificialInterruption of Fusion

By far the most commonly encountered form ofacute strabismus in clinical practice is that whichoccurs after temporary occlusion of one eye inpatients with no previous history of disturbance ofbinocular vision or in the course of treatment ofamblyopia in patients without strabismus (aniso-metropic amblyopia). When the patch is removed,the occluded eye will be in an esotropic positionor, in adults with large angle exophoria, occasion-ally in an exotropic position. This disturbing eventhas been reported when one eye has been band-aged for several days, after a perforating cornealinjury,128 after excision of a chalazion,21 or, as inCase 16–6, after swelling of the lids followingblunt trauma. Swan278 reported a group of patientsin whom a large angle esotropia developed inthe course of occlusion therapy for amblyopia. Inseveral of them, surgery was necessary tostraighten the eyes.

CASE 16–6

Age: 5 yearsMarch 17, 1971

Routine eye examination, no visual complaints

Esodeviations 339

Visual acuity: OD 6/4.5 OS 6/4.5Refraction: OD � 1.50D sph OS �1.25D sphDistance deviation: 8� esophoriaNear deviation: 10� esophoria

September 30, 1971The patient was struck in the OS with a shovel 2days before the examination; the OS was swollenand shut. When swelling subsided, the patientnoted diplopia. Slit-lamp examination revealed mildtraumatic iritis OS.

Distance deviation: 18� esotropia (comitant)Near deviation: 45� esotropia (comitant).

The OS was atropinized because of traumatic iritis.October 12, 1971

Esotropia is unchanged. Iritis has subsided. Glasseswith refractive findings as per visit on March 17were prescribed.

November 23, 1971The patient has worn glasses well, and diplopia hasdisappeared.

Distance deviation (cc): 4� esophoriaNear deviation (cc): 4� esophoriaDistance deviation (sc): 8� esophoriaNear deviation (sc): 16� intermittent esotropiaRx: Continue to wear glasses

June 9, 1972No complaints

Distance deviation (cc): orthophoriaNear deviation (sc): 6� esophoriaDistance deviation (sc): 6� esophoriaNear deviation (sc): 14� esophoria

Glasses were removed, and the patient has beenvisually comfortable without correction since thislast examination.

The child in Case 16–6 had an esophoria thatdecompensated and became manifest after artifi-cial disruption of fusion. The deviation wasreadily controlled with glasses, and eventually fu-sional amplitudes recovered sufficiently to controlthe deviation without glasses.

Occlusion of one eye presents an obstacle tobinocular vision since it disrupts fusion. Oncefusion is disrupted and the compensatory mecha-nism is thus suspended, a formerly latent esodevi-ation will become manifest. In some patients, cor-rection of the underlying refractive error willstraighten the eyes. In others, the deviation is of atemporary nature and will disappear spontane-ously. In another group, surgery may be indicated.The prognosis for restoration of normal binocularvision is excellent, although improvement is notalways so spontaneous, and in some patients sur-gery may become necessary. It is prudent to per-form a refraction before considering patching one

eye for whatever reason. In the presence of asignificant uncorrected hypermetropic refractiveerror, the patient should be warned that an esotro-pia may ensue from wearing the patch.

Acute Esotropia Without PrecedingDisruption of Fusion (Burian-Franceschetti Type)This form of strabismus is characterized by anacute onset with diplopia, a relatively large angleesotropia, absence of signs of paralysis, and agood potential for binocular cooperation. The re-fractive error, as a rule, is insignificant and theaccommodative element is minimal. Disruption offusion is not an etiologic factor, and in mostinstances the deviation apparently occurs sponta-neously. However, in some patients a debilitatingillness or physical or emotional stress may precedethe onset of the deviation.

This form of acute strabismus was first de-scribed by Burian,33 who reported on four patientsranging in age from 11 to 72 years who hadesotropia of acute onset and diplopia. All had lowhypermetropic refractive errors, and the angle ofstrabismus ranged from 20� to 60�. In all patientsthere was good binocular cooperation with theangle of strabismus corrected, and the functionalresults following surgery were excellent. Addi-tional cases were reported by Franceschetti,95 andFranceschetti and Bischler96 and this form of stra-bismus has become associated with Franceschetti’sname in the European literature. Several additionalcases have been reported,44 and the literature wasreviewed by Burian and Miller.35 It appears thatsuch patients have an asymptomatic esophoriawith only a slim reserve of fusional amplitude thatmaintains alignment of the eyes over the years butthat may become lost under the influence of physi-cal or emotional strain. In addition to a favorableoutcome after surgical management of this condi-tion33 good results have also been obtained afterchemodenervation.68 We feel that surgical correc-tion of acute-onset comitant esotropia in childrenunder 5 years of age who are neurologically nor-mal should not be delayed for longer than a fewmonths to avoid the development of suppressionand amblyopia. In visually mature children andadults this risk no longer exists and a longer delayof surgery is tolerated.222

Acute Esotropia of NeurologicOriginThis potentially threatening event is fortunatelyrare but should always be kept in mind when


encountering acute-onset comitant esotropia. Asmentioned earlier in this chapter, a comitant eso-tropia with a gradual onset may occur in conjunc-tion with Arnold-Chiari malformation,2, 6, 177, 235

hydrocephalus,107 intracranial astrocytoma, andother brain tumors,3, 263, 264, 299 but the onset mayalso be sudden in any of these conditions. In thecase of craniocervical junction anomalies, suboc-cipital decompression should precede strabismussurgery since otherwise recurrence of the esotropiais common.297 Unlike in the two former forms ofacute esotropia, the functional results after surgicalalignment of the eyes are not always favorable inacute esotropia of neurologic origin.43, 297

Unless the cause of acute-onset esotropia isobvious, such as after artificial interruption ofbinocular vision or uncorrected hypermetropia, anunderlying neurologic condition should always beconsidered. Hoyt126 suggests that the presence ofnystagmus in such patients or failure to restorenormal binocular vision with surgery should besufficient cause to proceed with a neurologic eval-uation.

Microtropia

Ultrasmall angles of strabismus may escape diag-nosis by ordinary methods of examination andare frequently overlooked. The cover test may benegative, or the fixation movement of the deviatedeye may be absent or so small that it defies detec-tion by the examiner when the sound eye is cov-ered. Since amblyopia is a regular feature of mi-crotropia, such patients often are subjected to anextensive, costly, and quite unnecessary neuro-logic evaluation in an effort to establish the causeof reduced visual acuity in one eye.127

Thus microtropias are of considerable clinicalsignificance. In view of the confusion with respectto the terminology and clinical characteristics ofmicrotropias, a discussion of this entity must bequite detailed.

The ophthalmic literature has become redun-dant with descriptions of numerous forms of ul-trasmall angles of strabismus. Many authors haveintroduced their own definitions and terms forwhat often appear to be similar, overlapping, oreven identical clinical entities. Parks226 rightfullycomments on the monstrous semantic structurethat has evolved, including, among others, theterms retinal slip, fixation disparity, fusion dispar-ity, retinal flicker, monofixational esophoria,

monofixational syndrome, strabismus spurius, mi-crotropia unilateralis anomalo-fusionalis, micro-strabismus, and minisquint. At the present stageof our knowledge, it may be difficult and evenimpossible to bring order into this system. Beforeattempting to do so, a brief historical review ofultrasmall angle deviations is in order.

Historical Review

Irvine141 reported detailed studies on 16 apparentlynonstrabismic, anisometropic amblyopes in whomthe 4� base-out test elicited positive scotoma re-sponses and in whom close observation of thecorneal reflex revealed ‘‘only reasonably goodfixation.’’ This combination of amblyopia, aniso-metropia, and unsteady or possibly nonfoveal fix-ation may have been one of the first descriptionsof what is currently recognized as microstrabis-mus.

Irvine’s study was followed by several reportson small angle deviations characterized by fovealsuppression of the deviated eye and normal ornear-normal peripheral fusional amplitudes. Theseforms were referred to as ‘‘retinal slip’’ byPugh,242 ‘‘esophoria with fixation disparity’’ byGittoes-Davies,99 ‘‘flicker cases’’ by Bryer,32 and‘‘fusion disparity’’ by Jampolsky.143, 145 The termfixation disparity entered the discussion of smallangle strabismus, adding further to the confusionin terminology. Jampolsky, who uses the termfixation disparity interchangeably with fusion dis-parity, defines this as a heterophoria in which thereis no exact bifoveal fixation. In his opinion, fusion(fixation) disparity occupies an intermediate statebetween heterophoria and heterotropia.143, 145

Crone63 pointed out that gradual transitions existbetween orthophoria and microstrabismus; he con-siders fixation disparity a manifestation of abnor-mal binocular vision. Ogle and coworkers221 hadpreviously used the term fixation disparity to de-scribe a long-known minute maladjustment of thevisual axis ranging in magnitude from severalminutes to maximally 20 minutes of arc. It occursin subjects with heterotropia but also in those withnormal binocular functions, equal visual acuity ineach eye, and absence of suppression scotomas.Martens,185 a former coworker of Ogle, deploredthe usurping of this term by clinicians in referenceto anomalies of binocular vision and microstrabis-mus and stressed the fact that fixation disparity isa part of normal binocular vision.

Parks and Eustis233 and Parks224 applied the

Esodeviations 341

term monofixational phoria to patients with esode-viations in whom the angle of strabismus waslarger on the alternate cover than on the covertest. Parks believed that the deviation in this groupwas kept partially latent by peripheral fusion andthat macular suppression, normal retinal corre-spondence, mild degrees of amblyopia, gross ste-reopsis, and normal fusional vergences were otherfeatures of this entity. Peripheral fusion with nor-mal retinal correspondence was thought to be pos-sible in such cases on the basis of a ‘‘stretchedPanum’s area.’’

In a later paper, Parks226 presented his mostrecent thinking on the monofixational syndrome—to replace all terminology previously introducedby him. Patients with this syndrome are those inwhom a ‘‘macular’’ scotoma in one eye (monofi-xation), good peripheral fusion with fusional am-plitudes, and gross stereopsis are present consis-tently. Variable features associated with themonofixational syndrome are a history of strabis-mus, anisometropia, organic unilateral macular le-sions, amblyopia, nonfoveal fixation, orthophoria,small angle heterotropia, and possibly a deviationthat is larger on the alternate cover test than onthe cover test. The monofixational syndrome mayoccur (1) primarily because of inability to fusesimilar macular images, (2) secondary to treatmentof large angle strabismus, (3) secondary to aniso-metropia, and (4) secondary to a unilateral macu-lar lesion.

Lang166 introduced the terms microstrabismusand microtropia to describe small angle hetero-tropias of less than 5� associated with harmoniousanomalous retinal correspondence, partial stereop-sis, and mild amblyopia. He had reported thisform of heterotropia earlier in conjunction with aninconspicuous angle of the deviating eye163 andsummarized his studies on microtropia in a mono-graph.169 According to Lang’s concept, micro-tropia occurs in a primary and consecutive form.The primary form may remain constant duringlife, or the angle of heterotropia may increase(decompensating primary microtropia). Lang173 re-cently proposed that primary microtropia may berelated to the strong dominance of the fixatingeye. The nondominant eye fails to track preciselyin unison with the dominant eye, the binocularconnection is loosened, and microstrabismus withanomalous correspondence develops. Consecutivemicrotropias are caused by surgical or optical cor-rection of a large angle heterotropia and are a

common finding after surgical alignment of essen-tial infantile esotropia.

Three types of microstrabismus can be differen-tiated according to the fixation behavior: (1) cen-tral fixation; (2) eccentric fixation and anomalousretinal correspondence, the angle of the anomalybeing larger than the degree of eccentricity offixation; and (3) an angle of anomaly identical tothe degree of eccentricity of the monocular fixa-tion (microtropia with identity). Lang thus in-cludes patients in whom the cover test is positive,(1) and (2), and those in whom it is negative, (3).Lang165 also stressed the frequent occurrence offamilial microtropia and drew the interesting butunsupported conclusion that anomalous correspon-dence in these patients is a primary and hereditarydefect, but revised this opinion recently.173 Hol-land129 and Richter247 had previously discussedthis possibility in connection with small angledeviations. Cantolino and von Noorden39 reportedan uncommonly high prevalence of sensory, mo-tor, and refractive anomalies in families with mi-crotropic propositi, but rejected the concept thatmicrotropia is a primary congenital defect. Rather,they believe that microtropia is the result of multi-ple and independently inherited refractive, sen-sory, or motor anomalies.

Helveston and von Noorden120 questionedwhether some of the strabismus forms that Langhad placed in the category of microtropia aresufficiently specific or different from those longknown and accepted by ophthalmologists as‘‘small angle deviations’’ to deserve a special clas-sification. They suggested that the term micro-tropia be reserved to describe a unique form ofsensorial adaptation in which the cover test isnegative and amblyopia, eccentric fixation, andharmonious anomalous retinal correspondence arepresent (type 3 of Lang). In these cases, the angleof heterotropia equals the distance between thefovea and the area of eccentric fixation. The ec-centric area is used for binocular as well as formonocular fixation; therefore the cover test willbe negative because a fixation movement is notrequired when the fixating eye is covered. Periph-eral fusion with fusional amplitudes and grossstereopsis are usually present. The functional com-pleteness of sensorial adaptation in microtropia,as defined by Helveston and von Noorden,120 isemphasized further by their finding that hetero-phorias may be present in a direction opposite thatof microtropia (exophoria with microesotropia).Cuppers65 had previously pointed out that there


are patients with eccentric fixation in whom thedegree of eccentricity of fixation under monocularconditions and the angle of anomaly under binocu-lar conditions are identical. Holland127 describedcases of amblyopia, an inconspicuous angle ofesotropia, and anomalous retinal correspondencethat were identical to those currently being classi-fied as microtropia.

The high incidence of anisometropia in patientswith microtropia suggests a possible etiologic rela-tionship.120, 158, 256 Von Noorden200 assumed that,unlike other forms of strabismus in which suppres-sion occurs secondary to the motor anomaly, mi-crostrabismus may develop secondary to a fovealscotoma caused by uncorrected anisometropia dur-ing early infancy. With foveal function thus dimin-ished early in life and before the fixation reflex isfully developed, he postulated that the fixationreflex may become adjusted to extrafoveal retinalelements having a higher visual function than thefovea. Such an event may lead eventually to ec-centric fixation under monocular conditions and toanomalous retinal correspondence under binocularconditions.

Lang168 argued against Helveston and vonNoorden’s restricting the definition of microtropia.He pointed out that although fixation may be ec-centric in persons having microtropia, the degreeof eccentricity need not necessarily coincide withthe angle of anomaly. Thus he continues to grouptogether patients with central fixation (positivecover test), eccentric fixation without identity withthe angle of anomaly (positive cover test), andthose in whom identity exists (negative cover test).

Epstein and Tredici87 pointed out that micro-tropias do not occur exclusively with esodevi-ations but that there are also microexotropias thatcan be diagnosed only by using the 4� test base-in.

Current Concepts and ClinicalSignificance

From the foregoing reports and observations, it isobvious that a large spectrum of strabismus formsexist with inconspicuously small angles and vari-ous degrees of sensorial adaptations. Whether ad-ditional attempts to further categorize such devia-tions are clinically useful is debatable. Ontheoretical grounds, one could conceive of a spec-trum that ranges from normal binocular visionwith bifixation at one end, to fixation disparity asdefined by Ogle and coworkers,221 the variousmanifestations of microtropia, and small-angle es-

otropia at the other end. (See also de Decker andHaase.74) However, to force biological phenomenainto an orderly and rigid scheme that satisfies thehuman intellect is not always possible. A certainamount of overlap and variance is more in accor-dance with nature’s ways and will defy all suchattempts. We agree with Crone63 that it is moreimportant to analyze the binocular mechanism ineach patient than to set up artificial barriers by amultiplicity of terms and classifications.

For these reasons, none of the definitions andclassifications of ultrasmall angles of strabismuscurrently in use is without flaw. For instance,the monofixational syndrome of Parks226 includespatients without manifest strabismus and with nosensory anomalies other than a unilateral fovealscotoma. Strictly speaking, this latter entity wouldhave no place in a discussion of strabismus wereit not for the fact that, in patients with essentialinfantile esotropia, unilateral foveal suppressionunder binocular conditions occurs invariably asan end state after complete surgical alignment isachieved.205, 225 The term monofixation is some-what misleading since fixation may occur witheach fovea in spite of the fact that a foveal sup-pression scotoma may be present. Also, the termfixation refers to seemingly steady maintenance ofthe image of the object of attention on the fovea,that is, to a motor rather than to a sensory process.Lang includes heterotropias as large as 5� in hisclassification of microtropia, although there are noobvious pathophysiologic or clinical differencesbetween an esotropia of 5� or, say, 10�. Thus theborderline between microtropia as defined byLang and a small angle esotropia is poorly de-fined. A small angle esotropia is said to be presentwhen the deviation is cosmetically noticeable butnot disfiguring.169 Whether strabismus presents acosmetic problem depends, among other factors,on the facial configuration of the patient since acertain angle of strabismus can be inconspicuousin one patient and cause a significant cosmeticdisfigurement in another. It is therefore somewhatarbitrary when Lang refers to small angle esotro-pia when the deviation is between 5� and 12�and large angle strabismus when the deviationexceeds 12�.

The group singled out by Helveston and vonNoorden120 is unique in regard to completeness ofsensorial adaptation, but the relationship betweenthe degree of eccentricity of unilateral fixation andthe angle of anomaly under binocular conditionscannot always be established unequivocally.199

Esodeviations 343

Anisometropia, though often associated with micro-tropia as defined by these and other authors,158, 256

is not a consistent finding and anisometropic am-blyopia may occur without microtropia.110 On theother hand, the anisometropia may no longer bepresent when the diagnosis of microtropia ismade.198 The patient material published byLang,169 the patient in Case 16–7 (see below), andseveral other patients with primary microtropiaand emmetropia observed by us add support toLang’s contention that primary microtropia, unre-lated to anisometropia, is a distinct entity. In viewof the clinical importance of ultrasmall heterotro-pias and the confusion in the literature to whichalmost everyone writing on this subject has addeda share, the following synthesis appears useful.

In addition to large and small angle esodevi-ations with specific sensory and motor characteris-tics, manifest esodeviations with inconspicuouslysmall angles also exist. We have adopted Lang’smicrostrabismus or microtropia as an appropriateterm to describe these deviations. Consistent find-ings in such patients are amblyopia; abnormalretinal correspondence (as determined with theBagolini striated glasses or the foveo-foveal testof Cuppers); relative scotoma on the fovea or, inthe case of parafoveal fixation, the fixation pointof the deviated eye (as determined with the 4�

base-out or base-in prism tests, the Bagolini test,or with binocular perimetry); normal or near-nor-mal peripheral fusion with amplitudes; and defec-tive stereoacuity (see Table 16–4). Variable find-ings include the size of the deviation, foveal ornonfoveal fixation behavior, identity between thedegree of eccentric fixation and the angle of anom-aly, the presence or absence of anisometropia, andpositive or negative cover test results.

Microtropia is a stable condition in most pa-tients but not a guarantee against subsequent dete-rioration into larger deviation as shown by manystudies.7, 123, 291

Diagnosis

When the cover test is negative or the fixationmovement of the deviated eye is inconspicuouslysmall so that it escapes detection by the examiner,the diagnosis of microtropia may be difficult. Inall other cases the diagnosis is clearly establishedby a very small fixation movement (flick) of thedeviated eye upon covering the fixating eye. Whenthe cover test is negative, however, special diag-nostic procedures must be used to differentiate

a microtropia with identity from nonstrabismicabnormalities causing decreased visual acuity inone eye. A cycloplegic refraction should be car-ried out at the beginning of such an examinationsince microtropia occurs frequently with anisome-tropic amblyopia. Examination of the fixation pat-tern (see Chapter 15) will establish whether foveo-lar or parafoveolar fixation is present. The findingof nonfoveolar fixation in the amblyopic eyeclearly establishes the diagnosis of microtropia(Fig. 16–8). Identification of microtropia is moredifficult in isometropic patients and in those withminute degrees of fixation anomalies, for the merepresence of a fixation spot scotoma, diagnosedwith the Bagolini striated glasses (see p. 228),polarized visual acuity charts, or the 4� base-out(see p. 218) or base-in prism cover test does notestablish unequivocally whether the underlyingcause is functional, as in microtropia, or organic.Likewise, stereoacuity is reduced not only withfunctional amblyopia but also when foveal func-tion is reduced by organic lesions. In such pa-tients, the foveo-foveal test of Cuppers (see p.230) may be helpful (see Chapter 15). The findingof a minute angle of anomalous retinal correspon-dence clearly identifies the patient as having mi-crotropia, even if the results of the cover test arenegative or the amplitude of the fixation move-ment of the amblyopic eye is too small to detectwhen the sound eye is covered. Fusional ampli-tudes (on the basis of anomalous retinal correspon-dence) can be elicted with rotary prisms or on theamblyoscope and recordings of binocular VEPsare consistent with the presence of peripheral fu-sion.276

A microtropia should always be suspected inunilateral decrease of visual acuity for which noorganic cause can be found in patients withoutapparent strabismus or a history of such and with-out significant refractive errors or anisometropia.Extensive neuro-opthalmologic evaluations andparental fears of an intracranial lesion can beavoided by making the correct diagnosis, as shownin Case 16–7.

CASE 16–7

A 6-year-old boy was examined for a second opinion.During a routine eye examination about 1 year agovisual acuity OS was found to be decreased. An-other ophthalmologist found no cause for this prob-lem and suggested a neurologic consultation and


FIGURE 16–8. Microtropia with identity.A, Eyes appear straight. Mild amblyopiaOD. The central suppression scotoma ODhas led to parafoveolar fixation. B, Covertest fails to reveal a fixation movement.OD continues to fixate with the same ex-trafoveolar elements used for fixationwhen both eyes were open. C, Visuscopereveals fixation OD 2� to 3� nasal to and1� below the foveola. (From Noorden GKvon: Atlas of Strabismus, ed 4. St Louis,Mosby–Year Book, 1983.)

computed tomography scan of the skull. There wasno history of strabismus. The medical history wasnegative. One maternal aunt had strabismus in child-hood for which surgery had been performed. Onexamination visual acuity was 6/9 OD and 6/60 OSwhen tested with Snellen letters. The cover andcover-uncover tests were negative at near and dis-tance fixation. The 4� prism test gave a scotomaresponse OS. Cycloplegic refraction was �1.00 sphOU. Anterior segments and fundi were normal. Ex-amination of the fixation behavior by direct ophthal-moscopy showed steady foveolar fixation OD andunsteady parafoveolar fixation with an area 2� aboveand nasal to the foveola OS. There was anomalousretinal correspondence with the Bagolini and foveo-foveal test of Cuppers. The patient had no stereop-sis on random-dot tests, and his fusional amplitudeswere normal. We diagnosed a primary microtropia

and since the child had never been treated andvisual acuity OS was very low, ordered total occlu-sion of OD for 2 months. The patient returned 21⁄2months later with a visual acuity of 6/9 OD and6/15 OS. Continued occlusion treatment for another41⁄2 months resulted in a final visual acuity of 61⁄2OS.

Therapy

Microtropia in the older child or adult does notrequire therapy. On the contrary, we feel that treat-ment in such patients is ill advised, for eliminationof the central scotoma may cause intractable di-plopia. Such patients have comfortable and nearlynormal binocular vision with good peripheral fu-sional amplitudes. In young children up to 6 years

Esodeviations 345

of age, however, attempts should be made to treatthe amblyopia. If significant anisometropia is pres-ent, we occlude the fixating eye and prescribe thefull refractive correction. We have observed manypatients in whom the microtropia disappeared un-der energetic occlusion therapy. Fixation of theamblyopic eye changed from parafoveal to centraland steady, visual acuity reached a level of 6/6,retinal correspondence became normal, and ster-eoacuity improved from 100 to 40 seconds of arc.Other authors have made similar observa-tions.47, 115, 130, 149

The fact that microtropia, if diagnosed andtreated in the young child, can be cured refutesthe concept of an underlying primary congenitaldefect of retinal correspondence, as proposed byseveral authors.129, 163–168, 247

Recurrent Esotropia

An unusual form of esotropia which recurs relent-lessly to the same angle despite multiple opera-tions but is fortunately rare was identified by vonNoorden and Munoz214 in 19 of 3000 patients whounderwent surgery for esotropia of the essentialinfantile type or with an onset in early childhood.Among the factors that could conceivably causesuch a condition one must consider an increase ofuncorrected hypermetropia, a deep-seated anoma-lous retinal correspondence, nystagmus blockageby convergence, an unstable AC/A ratio, or a blindspot syndrome. None of these factors could beimplicated in the patients we studied and the causeof recurrent esotropia for which we used the clini-cal jargon ‘‘malignant’’ esotropia remains un-known.

Secondary Esotropia

Sensory Esotropia

Etiology and Clinical Characteristics

Reduced visual acuity in one eye presents a severeobstacle to sensory fusion and in fact may abolishthe fusion mechanism altogether. The ensuing stra-bismus is the direct consequence of a primarysensory deficit, and in such cases the term sensoryheterotropia is used. Obviously, the origins ofsensory esotropia are numerous, limited only bythe number of pathologic conditions that can af-fect visual acuity in one eye. The most common

causes are anisometropia, injuries, corneal opacit-ies, congenital or traumatic unilateral cataracts,macular lesions, and optic atrophy.

In the past it was thought that whether or nota sensory esotropia or exotropia developed de-pended on the age of the patient at the time ofvisual acuity decrease in one eye. For instance,Chavasse40 stated that eyes that are congenitallyblind or have lost vision shortly after birth diverge.Hamburger,106 on the other hand, wrote that mosteyes with congenital unilateral blindness or severevisual impairment in early childhood converge.There is similar disagreement in the literature asto the direction of strabismus when the onset ofvisual impairment occurs during later childhoodor adolescence. We have analyzed the records of121 patients with sensory heterotropia and haveencountered esotropia and exotropia of almostequal frequency when the onset of visual impair-ment occurred at birth or between birth and 5years of age.261 Exotropia predominated in olderchildren and adults (Fig. 16–9), and there was nocorrelation between the degree of visual impair-ment and the development of esotropia or exotro-pia. Similar observations were reported byBielschowsky19 and by Broendstrup.29 We alsoencountered a strikingly high prevalence of over-acting inferior and superior oblique muscles inpatients with sensory esodeviations or exodevi-ations.261 This association, which has also beennoted by other investigators,144, 249 does not have asatisfactory explanation at this time. A prevalenceof dissociated vertical deviations in 12.5% of pa-tients with sensory heterotropias may be explainedon the basis of loss of fusion.161

Several authors have commented on the fre-quent association between unilateral visual lossfrom birth or with onset in early infancy, withesotropia, manifest latent nystagmus with a nullin adduction, fixation preference in adduction, anda head turn toward the side of the fixating eye.27,

109, 117 Spielmann266–268 coined the term functionalmonopthalmic syndrome for this entity and sug-gested that these signs, together with optokineticasymmetry, are manifestations of optomotor im-maturity from lack of normal binocular input dur-ing early infancy.

It is not entirely clear why some patients be-come esotropic and others exotropic when theylose sight in one eye. Bielschowsky19 explainedthe increased incidence of sensory exotropia withadvancing age as a gradual change of topographic-anatomical orbital factors in adolescence, favoring


FIGURE 16–9. Frequency distribution of the type of sensory deviation as a function of the age ofonset of visual loss. ESO, esotropia; EXO, exotropia. (From Sidikaro Y, Noorden GK von: Observationsin sensory heterotropia. J Pediatr Ophthalmol Strabismus 19:12, 1982.)

divergence rather than convergence. This explana-tion is difficult to reconcile with the fact that theorbital axes actually converge slightly betweenbirth and adulthood.183 The notion that the visuallyimpaired eye, suspended from fusional innerva-tion, drifts into a relative position of rest deter-mined by anatomical factors also does not explainwhy this position should be one of esotropia inone patient and of exotropia in another in thesame age group.

Worth301 speculated that the direction of a sen-sory heterotropia is determined by the refractiveerror of the sound eye; that is, the blind eye willdiverge if the sound eye is ametropic or myopicand will converge if the sound eye is hypermetro-pic. This assumption was not supported by ourdata, which showed an equal distribution of refrac-tive errors in various patient groups.261 Possibly,various degrees of tonic convergence during earlychildhood and perhaps less forceful tonic conver-gence during adulthood contribute to the directionof a sensory heterotropia.40 Sensory esotropia isusually comitant; however, we have examined pa-tients with a long-standing sensory esotropia inwhom limitation of abduction and excessive ad-duction were present. Forced duction tests in suchpatients reveal restriction of passive abduction, a

finding that must be interpreted as evidence forcontracture of the medial rectus or the conjunctiva,or both, and Tenon’s capsule.

The clinician must never forget that any typeof esotropia, whether diagnosed early in life or ata later stage, may be sensory and could be thefirst clinical sign of poor visual acuity or evenblindness in one eye. For this reason, we considerexamination of the entire globe to be an absolutelyessential part of the evaluation of all strabismicpatients, regardless of how transparent the clinicalsituation appears. For instance, Costenbader andO’Rourke56 described a number of children withoptic atrophy in whom the chief complaint whenfirst seen was strabismus. Ellsworth86 reported eso-tropia to be the second most common presentingsign of retinoblastoma.

Therapy

Treatment usually is directed toward improvingthe cosmetic appearance by means of surgicalcorrection since, in most instances, the very natureof sensory esotropia precludes restoration of bin-ocular function. An exception to this is childrenwith unilateral congenital or traumatic cataracts ofpostnatal development. In such patients, the grad-

Esodeviations 347

ual onset of an esotropia heralds disruption offusion, and cataract surgery should be performedwithout delay, followed by contact lens correction,occlusion treatment for the amblyopia, and eventu-ally by strabismus surgery. The longer the devia-tion is allowed to persist, the less likelihood thereis of binocular vision being restored after success-ful cataract surgery, especially in adults with ac-quired cataracts.286

When the patient is blind in one eye and ther-apy is aimed only at improving the cosmetic ap-pearance, a base-out prism before the blind eyemay be tried to make the deviation seem lessobvious. However, most patients require surgery,and an operation should not be discouraged be-cause of the remote chance that the eye mayeventually straighten spontaneously or even be-come exotropic. If that occurs, additional surgerycan be performed. There is no need for a patientto go through adolescence with a severe cosmetichandicap that will invariably have a negative psy-chological effect. In the presence of a head turntoward the side of the fixating eye (functionalmonophthalmic syndrome of Spielmann266–268),surgery must be performed on the normal eye tonormalize the head position.

Depending on the size of the deviation, weprefer to operate on the deviated eye and to per-form a recession of the medial rectus musclewhich may be combined with resection of thelateral rectus muscle and with an inferior obliquemyectomy if this muscle is found to be overacting.An esotropia that is present only at near fixationresponds well to posterior fixation of the medialrectus muscle at least 13 mm behind its insertion.If the forced duction tests are positive, a barescleral recession of the nasal conjunctiva and Ten-on’s capsule should be carried out. The surgicalresult in sensory esotropia is less predictable thanwhen visual acuity is normal in each eye, andadjustable sutures are helpful in improving thealignment postoperatively. Even though surgicalalignment of a sensory deviation may create astable result in many patients,84 the esotropia mayrecur or a consecutive exotropia may developyears after the first operation. The surgeon is ad-vised to inform patients of this possibility.

Consecutive Esotropia

Consecutive esotropia occurs almost exclusivelyiatrogenically after surgical overcorrection of anexodeviation. This complication and its manage-

ment are discussed in Chapter 17. A spontaneousconsecutive esotropia, that is, a change from exo-tropia into esotropia without exogenous mechani-cal factors or an acquired paralytic component, isa most extraordinary occurrence indeed. To ourknowledge only one case has been reported.91

Management of SurgicalOvercorrections

The etiology, management, and prevention ofovercorrections after strabismus surgery are dis-cussed in Chapter 26. Overcorrections can some-times be related to inadequate diagnosis and sub-sequent inappropriate surgical procedures. In thecase of an esotropic patient, this applies specifi-cally to disregard of an accommodative element,a high hypermetropic error, or vertical incomi-tance (A or V pattern). In other instances theyoccur without obvious cause and in spite of anappropriate amount of surgery.

The prevalence of consecutive exotropia is sur-prisingly low and, according to several large sur-veys, ranges between only 2% and 8% of allesotropes on whom surgery was performed.50, 300

Our own experience is in accordance with theseobservations.216 These figures contrast sharplywith the reported incidence of undercorrec-tions.205, 259

Except for large overcorrections with severerestriction of ocular motility, in which case disin-sertion of a muscle must be considered (see Chap-ter 26), the treatment of consecutive exotropia isone of watchful waiting. From a functional pointof view, recent data show that a surgical overcor-rection actually may be more beneficial than anundercorrection. The effect of strabismus surgeryon sensory adaptations, especially on the normal-ization of retinal correspondence, is well-known.151, 287 It seems that this effect can be en-hanced if consecutive exotropia is allowed to per-sist for some time; this has led some ophthalmolo-gists to strive intentionally for an overcorrection.67,

75, 133, 142, 252, 300 Even though a consecutive exotro-pia is far from being universally accepted as adesirable outcome of surgery for esotropia, thesedata show that waiting does no harm and mayeven be beneficial before a reoperation is consid-ered.

The nonsurgical management of consecutiveexotropia consists mainly of reduction of the spec-tacles correction if the patient is hypermetropic.


Although such measures may temporarilystraighten the eyes, they do not eliminate the basicproblem and may lead to accommodative astheno-pia in older children, depending on the degree ofundercorrection. Prisms base-in may be consid-ered in older patients to eliminate diplopia.

Alternate occlusion, immediately after surgery,is sometimes effective in reducing the exotropiaprovided that ocular motility is normal, that is, theexotropia is not caused by excessive recession ofthe medial rectus muscles. We have used thisapproach for many years and have been moder-ately succesful, particularly in patients withouthypermetropia. As a rule, consecutive exotropiadecreases with time, and should reoperation be-come necessary we prefer to wait at least 6 monthsbefore proceeding with it. The reader is referredto Chapter 26 for other aspects of the surgicalmanagement of overcorrections.

Esotropia Associated withVertical Deviations

Hyperdeviations frequently are found in associa-tion with esotropia. Symptoms in each patientmust be analyzed carefully since the clinical ne-glect of associated vertical deviations may se-verely jeopardize attempts to restore binocular vi-sion. The clinical manifestations of verticaldeviations are numerous. They may be comitantin all directions of gaze, incomitant and with allother characteristics of a paretic deviation, absentin primary position, manifest in lateral gaze only,or present as a dissociated vertical deviation. Ineach instance, one must consider whether the hy-perdeviation is primary or secondary in relation tothe underlying esodeviation.

Clinical Characteristics andDiagnosis

A small angle comitant hypertropia of not morethan 3� occurs in 50% of patients with constantesotropia and in 25% of all those with hetero-tropia.254 Ductions and versions may be essentiallynormal with no evidence of a paretic cycloverticalmuscle. The etiology of this deviation is unknown;however, during the prism and cover test, thephysician must rule out artifacts induced byoblique positioning of the prism.

Incomitant associated hyperdeviations can beplaced in two categories: (1) those caused by

paresis of one of the cyclovertical muscles and (2)those caused by primary or secondary overactionof one or both inferior or superior oblique mus-cles. A deviation of the first type is greatest whenfixating with the paretic eye in the field of actionof the paretic muscle and will exhibit all character-istics consistent with a cyclovertical paresis (seeChapter 18). The degree of esotropia often issmall, and in such instances the vertical deviationis primary while the esotropia is secondary todisruption of fusion by the hypertropia. Wepointed out earlier in this chapter that duringchildhood an esodeviation is a common responseto interruption of fusion.

Deviations of the second type are characterizedby overaction of one or both inferior oblique mus-cles, usually associated with a V pattern (seeChapter 19). Such patients exhibit the characteris-tic elevation of the adducted eye (strabismus sur-soadductorius; see Chapter 18), and when theinvolvement is bilateral, they have a large righthypertropia in levoversion and a large left hyper-tropia in dextroversion. With the eyes in primaryposition, the hypertropia may be small or nonexis-tent. Overaction of the superior oblique muscles,usually associated with an A pattern, is less com-mon in esotropes. Overaction of one or both infe-rior or superior oblique muscles may be secondaryto weakness of their ipsilateral antagonists, orapparently primary if dysfunction of the antago-nists cannot be established, in which case thegeneric term elevation or depression in adductionis preferable. As pointed out earlier in this chapterapparent overaction of the inferior obliques, en-countered frequently in patients with essential in-fantile esotropia, must be distinguished from adissociated deviation.

The etiology and differential diagnosis of ele-vation in adduction is discussed in Chapter 18. Inthis chapter it is necessary to say only that someinvestigators have interpreted the apparently pri-mary overaction of the inferior oblique musclesin patients with horizontal strabismus as beingsecondary to the horizontal deviation since theoblique dysfunction may disappear after horizontalsurgery.21, 51

Brief mention must be made of the hyperdevi-ations that occur, often to the great chagrin ofthe surgeon, after surgery for esotropia has beenperformed. In such cases, it is commonly believedthat while reinserting one or both of the horizontalrectus muscles the surgeon inadvertently selecteda new site either above or below the horizontal

Esodeviations 349

meridian of the globe. Foster and Pemberton,94

however, reported that purposely raising or low-ering the insertion of the horizontal rectus musclesproduces only a relatively small hyperdeviation(up to 11�). Many surgeons actually use this effectof vertical transposition of the horizontal musclesto correct small degrees of associated hyperdevia-tion (see Chapter 25).

Scobee254, p. 387 also mentioned the possibilitythat hypertropia, when occurring postoperatively,actually may have been present before surgerybut was not apparent on routine examination. Hepostulated that a hyperdeviation in associationwith an esodeviation is a manifestation of mechan-ical superiority of the inferior over the superioroblique muscle when the eye is in extreme adduc-tion and cannot fixate, the fixation object beinghidden by the nose. Against this view one mayargue that the inferior or superior oblique musclesdo not necessarily overact when the fixation objectis no longer visible.

Finally, when large degrees of hypertropia oc-cur postoperatively, consideration must always begiven to the fact that surgery may have beenperformed erroneously on a vertical rather thanon a horizontal muscle. How to avoid this veryperturbing but by no means unprecedented com-plication is discussed in Chapter 26.

Therapy

In patients with primary paretic vertical deviationsin whom esotropia develops secondary to disrup-tion of fusion, therapy is nonsurgical (prisms) orsurgical, depending on the amount and type ofdeviation (see Chapter 20). In such cases, weprefer first to correct the vertical deviation andafter surgery to reevaluate the need for additionalcorrection of the horizontal deviation.

In patients in whom one or both inferioroblique muscles are overacting, myectomy of theoblique(s) is combined with horizontal muscle sur-gery (see also therapy of V esotropia, Chapter 19).

REFERENCES

1. Abraham S: Present status of miotic therapy in nonpara-lytic convergent strabismus. Am J Ophthalmol 51:1249,1961.

2. Akman A, Dayanur V, Sanac A, Kansu T: Acquiredesotropia as presenting sign of craniocervical junctionanomalies. Neuro Ophthalmol 15:311, 1995.

3. Anderson WD, Lubow M: Astrocytoma of the corpuscallosum presenting with acute comitant esotropia. Am JOphthalmol 69:594, 1970.

4. Apers R: Reponse a M. von Noorden. Bull Soc BelgeOphtalmol 221/222:269, 1987.

5. Archer SM, Helveston EM, Miller KK, Ellis FD: Stere-opsis in normal infants and infants with congenital eso-tropia. Am J Ophthalmol 101:591, 1986.

6. Arruga A: The time factor in strabismus surgery. InLuntz HM, ed: Proceedings of the First South AfricanInternational Ophthalmological Symposium. London,Butterworths, 1969, p 67.

7. Arthur BW, Smith JT, Scott WE: Long-term stabilityof alignment in the monofixation syndrome. J PediatrOphthalmol Strabismus 26:224, 1989.

8. Astle WF, Miller SJ: Acute esotropia: A sign of intracran-ial disease. Jpn J Ophthalmol 29:151, 1994.

9. Atkinson J: Development of optokinetic nystagmus inthe human infant and monkey infant. In Freeman RD,ed: Developmental Neurobiology of Vision. New York,Plenum Press, 1979, p 277.

10. Aust W: Indikationen zur Fruhbehandlung schielenderKinder. Klin Monatsbl Augenheilkd 154:686, 1959.

11. Baekeland L, Boschi A, Hoffmann D, Spiritus M: Oculartorticollis without normal binocular vision-head tilts. InLenk-Schafer M, ed: Orthoptic Horizons. Transactions ofthe Sixth International Orthoptic Congress, Harrogate,England, LIPS 1987, p 184.

12. Baker FH, Grigg P, Noorden GK. von: Effects of visualdeprivation and strabismus on the response of neurons inthe visual cortex of the monkey including studies on thestriate and prestriate cortex in the normal animal. BrainRes 66:185, 1974.

13. Baker JD, De Young-Smith M: Accommodative esotropiafollowing surgical correction of congenital esotropia, fre-quency and characteristics. Graefes Arch Clin Exp Oph-thalmol 226:175, 1988.

14. Baker JD, Parks MM: Early onset accommodative esotro-pia. Am J Ophthalmol 90:11, 1980.

15. Barlow HB, Blakemore C, Pettigrew JD: The neuralmechanism of binocular depth discrimination. J Physiol(Lond) 193:327, 1967.

16. Berard PV: ‘‘Early-delayed’’ treatment of strabismus ver-sus late treatment. In Ferrer ON, ed: Ocular Motility. IntOphthalmol Clin 11:103, 1971.

17. Berard PV, Reydy R, Berard P V Jr: Surgery of accom-modative esotropia. In Lenk-Schafer M, ed: OrthopticHorizons, Transactions of the Sixth International Or-thoptic Congress, Harrogate, England, LIPS, 1987, p 396.

18. Berke RN: Requisites for postoperative third degree fu-sion. Trans Am Acad Ophthalmol Otolaryngol 62:38,1958.

19. Bielschowsky A: Uber die relative Ruhelage der Augen.Ber Vers Dtsch Ophthalmol Ges. 34:67, 1913.

20. Bielschowsky A: Das Einwartsschielen der Myopen. BerDtsch Ophthalmol Ges 43:245, 1922.

21. Bielschowsky A: Lectures on Motor Anomalies. Han-over, NH, Dartmouth College Publications, 1943/1956.

22. Biglan AW, Gan XL: Experience with botulinum A toxin(oculinum) in the treatment of strabismus. Contemp Oph-thalmol. Forum 5:230, 1987.

23. Birch EE, Stager DR: Monocular acuity and stereopsisin essential infantile esotropia. Invest Ophthalmol Vis Sci26:1624, 1985.

24. Birch E, Stager D, Everett MMF: Random dot stereoacu-ity following surgical correction of infantile esotropia. JPediatr Ophthalmol Strabismus 32:231, 1995

25. Birch E, Stager D, Wright K, Beck R: The natural historyof infantile esotropia during the first six months of life.J Pediatr Ophthalmol Strabismus 2:325, 1998.

26. Bixenman WW, Laguna JF: Acquired esotropia as initialmanifestation of Arnold-Chiari malformation. J PediatrOphthalmol Strabismus 24:83, 1987.

27. Bourron-Madignier M: Unilateral congenital organic am-blyopia and manifest-latent nystagmus. In Kaufmann H,


ed: Transactions of the 16th Meeting of the EuropeanStrabismological Association, Giessen, Germany, 1987,p 235.

28. Bourron-Madignier M, Ardoin ML, Cypres C, Vettard S:Study of optokinetic nystagmus in children. In Lenk-Schafer M, ed: Orthoptic Horizons, Transactions of theSixth International Orthoptic Congress, Harrogate, Eng-land, LIPS, 1987, p 134.

29. Broendstrup P: The squinting position of weak-sightedeyes. Acta Ophthalmol 20:386, 1944.

30. Brown EVL: Net average yearly changes in refraction ofatropinized eyes from birth to beyond middle life. ArchOphthalmol 19:719, 1938.

31. Brown EVL, Kronfeld PC: Refractive curve in the U.S.A.with special reference to changes in the first two decades.C R Concilium Ophthalmol 13:87, 1929.

32. Bryer J: Aetiology and treatment of small convergentdeviations associated with a low degree of hypermetropia(letter). Br Orthopt J 10:85, 1953.

33. Burian HM: Motility clinic: Sudden onset of comitantconvergent strabismus. Am J Ophthalmol 28:407, 1945.

34. Burian HM: Hypermetropia and esotropia. J Pediatr Oph-thalmol 9:135, 1972.

35. Burian HM, Miller JE: Comitant convergent strabismuswith acute onset. Am J Ophthalmol 45:55, 1958.

36. Calcutt C, Murray ADN: Untreated essential infantileesotropia: Factors affecting the development of amblyo-pia. Eye 12:167–172, 1998.

37. Campos EC: Eradicating amblyopia before surgery (let-ter). J Pediatr Ophthalmol Strabismus 35:6, 1998.

38. Campos EC: Essential infantile esotropia (ESA Lecture).In Spiritus M, ed: Transactions of the 25th Meeting ofthe European Strabismological Association. Buren, TheNetherlands, Aeolus Press, 2000, p. 4.

39. Cantolino SJ, Noorden GK von: Heredity in microtropia.Arch Ophthalmol 81:753, 1969.

40. Chavasse FB: Worth’s Squint or the Binocular Reflexesand the Treatment of Strabismus, ed 7. London, BailliereTindall & Cox, 1939, p 519.

41. Chettibi A, Berkani M: Traitement chirurgical du strabi-sme accommodatif. A propos de 100 cas de esotropie.Ophtalmologie 2:303, 1988.

42. Ciancia A: La esotropia en el lactante, diagnostico ytratamiento. Arch Chil Oftalmol 9:117, 1962.

43. Ciancia A: On infantile esotropia with nystagmus inabduction. J Pediatr Ophthalmol Strabismus 32:280,1995.

44. Clark AC, Nelson LB, Simon JW, et al: Acute acquiredcomitant esotropia. Br J. Ophthalmol 73:636, 1989.

45. Clark RA, Miller JM, Rosenbaum AL, Demer JL: Hete-rotonic rectus muscle pulleys or oblique muscle dysfunc-tion? Am Assoc Pediatr Opthalmol Strabismus 2:17–25,1998.

46. Clark WN, Noel LP: Vanishing essential infantile esotro-pia. Can J Ophthalmol 17:100, 1982.

47. Cleary M, Houston CA, McFazdean R, Dutton GN: Re-covery of microtropia: Implications for etiology and neu-rophysiology. Br J Ophthalmol 82:225, 1998.

48. Coats DK, Paysse EA: Rectus muscle recession and re-section without scleral sutures. J Am Assoc Pediatr Oph-thalmol Strabismus 2:230, 1998.

49. Coats DK, Avilla CW, Paysse E, et al: Early onset refrac-tive accommodative esotropia. J Am Assoc Pediatr Oph-thalmol Strabismus 2:275, 1998.

50. Cooper E: The surgical management of secondary exotro-pia. Trans Am Acad Ophthalmol Otolaryngol 65:595,1961.

51. Cords R: Strabismus surso-adductorius. Ber Dtsch Oph-thalmol Ges 43:158, 1922.

52. Costenbader FD: Management of convergent strabismus.

In Allen JH, ed: Strabismus Ophthalmic Symposium I.St Louis, Mosby–Year Book, 1950, p 339.

53. Costenbader FD: Clinical course and management ofesotropia. In Allen JH, ed: Strabismus Ophthalmic Sym-posium II. St Louis, Mosby–Year Book, 1958, p 331.

54. Costenbader FD: Essential infantile esotropia. Trans AmOphthalmol Soc 59:397, 1961.

55. Costenbader FD: Sensorimotor examination of infants.In Arruga A, ed: International Strabismus Symposium.University of Giessen, Germany, 1966. Basel, S Karger1968, p 134.

56. Costenbader FD, O’Rourke TR: Optic atrophy in child-hood. J Pediatr Ophthalmol 5:77, 1968.

57. Costenbader FD, Ing M, Bair RV, Parks MM: Sympo-sium: Essential infantile esotropia. Am Orthopt J 18:5,1968.

58. Crawford MLJ, Noorden GK von: The effects of short-term experimental strabismus on the visual system inMacaca mulatta. Invest Ophthalmol Vis Sci 18:496,1979.

59. Crawford MLJ, Smith EL, Harwerth RS, Noorden GKvon: Stereoblind monkeys have few binocular neurons.Invest Ophthalmol Vis Sci 25:779, 1984.

60. Crawford MLJ, Noorden GK von, Meharg LS et al:Binocular neurons and binocular function in monkeysand children. Invest Ophthalmol Vis Sci 24:491, 1983.

61. Crone RA: Alternating hyperphoria. Br J Ophthalmol38:591, 1954.

62. Crone RA: Heterophoria. II. Fusion and convergence.Graefes Arch Clin Exp Ophthalmol 177:66, 1969.

63. Crone RA: From orthophoria to microtropia. Br OrthoptJ 26:45, 1969.

64. Crone RA: A new theory about heterophoria. Ophthalmo-logica 162:199, 1971.

65. Cuppers C: Grenzen und Moglichkeiten der pleoptischenTherapie. In Hollwich F, ed: Schielen-Pleoptik-Orthoptik-Operation. Stuttgart, Ferdinand Enke Verlag, 1961, p 32.

66. Cuppers C: Die Penalisation. Schielbehandlung 3:126,1971.

67. Dankner SR, Mash AJ, Jampolsky, A: Intentional surgicalovercorrection of acquired esotropia. Arch Ophthalmol96:1848, 1978.

68. Dawson ELM, Marshman WE, Adams GGW: The roleof botulinum toxin A in acute-onset esotropia. Ophthal-mology 106:1727, 1999.

69. de Decker W: Constant or apparently congenital esotro-pia? Invest Ophthalmol 6:61, 1982.

70. de Decker W: The Fadenoperation. In Lennerstrand G,Zee DS, Keller EL, eds: Functional Basis of OcularMotility Disorders. Wenner-Gren Symposium Series, vol37. Oxford, Pergamon Press, 1982, p 173.

71. de Decker W: Heterotropie (manifester strabismus). InKaufmann H, ed: Strabismus. Stuttgart, Ferdinand EnkeVerlag, 1986, p 141.

72. de Decker W: Langzeitresultate fruher Fadenoperationenbei fruhkindlichem Innenschielen. Z Prakt Augenheilkd18:257, 1997.

73. de Decker W, Dannheim-de Decker E: UnbeachteteZwangshaltungen beim fruhkindlichen Schielsyndrom.Klin Monatsbl Augenheilkd 215:95, 1999.

74. de Decker W, Haase W: Subnormales Binokular-sehen—Versuch einer Einteilung des Mikro-strabismus. Klin Monatsbl Augenheilkd 169:182, 1976.

75. de Decker W, Holzki U, Lauber V: Behandlung deranomalen Korrespondenz durch artifizielle Sekundardiver-genz. Ophthalmologica 157:142, 1969.

76. Deller M: Surgery of fully accommodative esotropia:Treatment, alternative or imposture? In Kaufmann H,ed: Transactions of the 20th Meeting of the EuropeanStrabismological Association. Brussels, Gahmig Press,1992, p 167.

Esodeviations 351

77. Deller M, Brack B: Erste Bilanz der modernen Schielbe-handlung. Klin Monatsbl Augenheilkd 155:712, 1969.

78. Dell’Osso LF: Congenital, latent or manifest-latent nys-tagmus. Similarities, difference and relation to strabis-mus. Jpn J Ophthalmol 29:351, 1985.

79. Demer JL, Noorden GK von: Optokinetic asymmetry inesotropia. J Pediatr. Ophthalmol Strabismus 25:286,1988.

80. Doden W: Neue Gesichtspunkte zur Atiologie des Schie-lens. Klin Monatsbl Augenheilkd 132:892, 1958.

81. Doden W, Adams W: Elektronystagmographische Ergeb-nisse der Prufung des optisch-vestibularen Systems beiSchielenden. Ber Dtsch Ophthalmol Ges 60:316, 1957.

82. Duffin EW: Practical Remarks on the New Operationfor the Cure of Strabismus or Squinting. London, JohnChurchill, 1840, p 77.

83. Dyer JA: Nonsurgical treatment of esotropia. In Sympo-sium on Strabismus. Transactions of the New OrleansAcademy of Ophthalmology. St. Louis, Mosby–YearBook, 1971, p. 154.

84. Edelman PM, Brown M: The stability of surgical resultsin patients with deep amblyopia. Am Orthopt J 27:103,1977.

85. Eizenman M, Westall CA, Geer I et al: Electrophysiologi-cal evidence of cortical fusion in children with early-onset esotropia. Invest Ophthalmol Vis Sci 40:354, 1999.

86. Ellsworth RM: The practical management of retinoblas-toma. Trans Am Ophthalmol Soc 78:478, 1969.

87. Epstein DL, Tredici TJ: Use of the four-diopter base-inprism test in microexotropia. Am J Ophthalmol 73:340,1972.

88. Esswein MB, Noorden GK von, Avilla CW: Hereditarymaldevelopment of visual motion pathway not found.Invest Ophthalmol Vis Sci 35(suppl):1829, 1994.

89. Fawcett S, Raymond JE, Astle WF, Skov CM: Anomaliesof motion perception in infantile esotropia. Invest Oph-thalmol Vis Sci 39:724, 1998.

90. Fells P, Berard PV, Gobin M, et al: Symposium onthe management of fully accommodative esotropia. InCampos C, ed: Strabismus and Ocular Motility Disorders.Proceedings of the Sixth Meeting of the InternationalStrabismological Association (ISA), Surfer’s Paradise,Australia. London, Macmillan, 1991, p 269.

91. Fitton MH, Jampolsky A: A case report of spontaneousconsecutive esotropia. Am Orthopt J 14:144, 1964.

92. Flynn JT: Vestibulo-optokinetic interaction in strabismus.Am Orthopt J 32:36, 1982.

93. Flynn JT, Grundmann S, Mashikian M: Binocular sup-pression of scotoma: Its role in phorias and intermittenttropias. Am Orthopt J 20:54, 1970.

94. Foster J, Pemberton EC: The effect of operative alter-ations in the height of the external rectus insertion. Br JOphthalmol 30:88, 1946.

95. Franceschetti A: Le strabisme concomitant aigu. Ophthal-mologica 123:219, 1952.

96. Franceschetti A, Bischler V: Strabisme convergent con-comitant aigu chez l’adulte. Confinia Neurol 8:380.1947/1948.

97. Friedman Z, Neumann E, Hyams SW, Peleg B: Ophthal-mic screening of 38,000 children age 1 to 21⁄2 years inchild welfare clinics. J Pediatr Ophthalmol Strabismus17:261, 1980.

98. Friedrich D, de Decker W: Prospective study of thedevelopment of strabismus during the first 6 months oflife. In Lenk-Schafer M, ed: Orthoptic Horizons, Transac-tions of the Sixth International Orthoptic Congress, Har-rogate, England, LIPS 1987, p 21.

99. Gittoes-Davies R: An examination of the aetiology andtreatment of small convergent deviations, associated witha low degree of hypermetropia. Br Orthopt J 8:71, 1951.

100. Gobin MH: La vision binoculaire apres correction chirur-gicale du strabisme accommodatif. Bull Mem Soc. FrOphtalmol 96:95, 1985.

101. Gobin MH: Longterm results of the surgical correction ofaccommodative squint. In Lenk-Schafer M, ed: Orthoptichorizons. Transactions of the Sixth International Or-thoptic Congress, Harrogate, England, LIPS, 1987, p 403.

102. Good WV, da Sa LC, Lyons CJ, Hoyt CS: Monocularvisual outcome in untreated early onset esotropia. Br JOphthalmol 77:492, 1993.

103. Graefe A von: Uber die von Myopie abhangige Formconvergirenden Schielens und deren Heilung. GraefesArch Clin Exp Ophthalmol 10:156, 1864.

104. Graham RA: Epidemiology of strabismus. Br J Ophthal-mol 58:224, 1974.

105. Gross SA, Esswein MB, Goldberg J, Noorden GK von:Asymmetric optokinetic nystagmus and pursuit inmonocular patients. Invest Ophthalmol Vis Sci35(suppl):1829, 1993.

106. Hamburger FA: Stellungsanomalien. In Velhagen K, ed:Der Augenarzt, vol 3. Stuttgart, Georg Thieme, 1960,p 88.

107. Happe W: Long-term results after bimedial posterior fix-ation sutures for infantile esotropia. Strabismus 5:117,1997.

108. Harcourt B: Ophthalmic complications of meningomyelo-cele and hydrocephalus in children. Br J Ophthalmol52:670, 1968.

109. Harcourt B, Spencer F: Manifest latent nystagmus affect-ing patients with uniocular congenital nystagmus. InGregersen E, ed: Transactions of the European Strabis-mological Association, Copenhagen, 1984, p 259.

110. Hardman Lea SJ, Snead MP, Loades J, Rubinstein MP:Microtropia versus bifoveal fixation in anisometropic am-blyopia. Eye 5:576, 1991.

111. Havertape SA, Whitfill CR, Cruz OA: Early-onset accom-modative esotropia. J Pediatr Ophthalmol Strabismus36:69, 1999.

112. Hayashi T, Iwashige H, Maruo T: Clinical features andsurgery for acquired progressive esotropia associated withsevere myopia. Acta Ophthalmol Scand 77:66, 1999.

113. Haynes H, White B, Held R: Visual accommodation inhuman infants. Science 148:528, 1965.

114. Held R: Normal visual development and its deviations.In Lennerstrand G, Noorden GK von, Campos E, eds:Strabismus and Amblyopia. Experimental Basis for Ad-vances in Clinical management. London, Macmillan,1988, p 247.

115. Helveston EM: Personal communication, 1973.116. Helveston EM: Dissociated vertical deviation: A clinical

and laboratory study. Trans Am Ophthalmol Soc78:734, 1981.

117. Helveston EM: Unilateral esotropia after enucleation ininfancy. Am J Ophthalmol 100:96, 1985.

118. Helveston EM: The 19th Annual Frank CostenbaderLecture—The origins of congenital esotropia. J PediatrOphthalmol Strabismus 30:215, 1993.

119. Helveston EM: The etiology of essential infantile (con-genital) esotropia, In Lennerstrand G, Ygge J (eds:) Ad-vances in Strabismus Research. Basic and Clinical As-pects. London, Portland Press, 2000, p 135.

120. Helveston EM, Noorden GK von: Microtropia: A newlydefined entity. Arch Ophthalmol 78:272, 1967.

121. Helveston EM, Ellis FD, Schott J, et al: Surgical treat-ment of congenital esotropia. Am J Ophthalmol 96:218,1983.

122. Helveston EM, Neely DF, Stidham DB, et al: Results ofearly alignment of congenital esotropia. Ophthalmolgy106:1716, 1999.

123. Hiles DA, Watson A, Biglan AW: Characteristics of es-


sential infantile esotropia following early bimedial rectusrecession. Arch Ophthalmol 98:697, 1980.

124. Hoffman KP: Neural basis for changes of the optokineticreflex in animals and men with strabismus and amblyo-pia. In Lennerstrand G, Noorden GK von, Campos E, eds:Strabismus and Amblyopia, London, Macmillan, 1988, p89.

125. Hoff-van Duin J van: Early and permanent effects ofmonocular deprivation on pattern discrimination and visi-omotor behavior in cats. Brain Res 111:261, 1976.

126. Hoyt CS: Acute onset concomitant esotropia: When is ita sign of serious neurological disease? Br J Ophthalmol79:498, 1995.

127. Holland G: Fehldiagnose bei bestehender Schielamblyo-pie. Klin Monatsbl Augenheilkd 139:287, 1961.

128. Holland G: Uber den akuten Strabismus convergens con-comitans. Klin Monatsbl Augenheilkd 140:373, 1962.

129. Holland G: Die anomale Korrespondenz als erworbene,bzw. angeborene, zum Teil familiar auftretende Anoma-lie. Ber Dtsch Ophthalmol Ges 65:471, 1964.

130. Houston CA, Cleary M, Dutton G, McFadzean RM:Clinical characteristics of microtropia—is microtropia afixed phenomenon? Br J Ophthalmol 823:219, 1998.

131. Hoyt CS: Abnormalities of the vestibulo-ocular responsein congenital esotropia. Am J Ophthalmol 93:704, 1982.

132. Hubel DH, Wiesel TN: Binocular interaction in striatecortex of kittens reared with artificial squint. J Neuro-physiol 28:1041, 1965.

133. Hugonnier R: The influence of the operative overcorrec-tion of an esotropia on abnormal retinal correspondence.In Arruga A, ed: International Strabismus Symposium.University of Giessen, Germany, 1966. Basel, S Karger,1968, p 307.

134. Hugonnier R, Clayette-Hugonnier S: Strabismus, Hetero-phoria, Ocular Motor Paralysis, Clinical Ocular MuscleImbalance. Translated and edited by Veronneau-TroutmanS. St Louis, Mosby-Year Book, 1969.

135. Hugonnier R, Magnard P: Les desequilibres oculomoteurobserves en cas de myopie forte. Ann Ocul 202:713,1969.

136. Ing MR: Early surgical alignment for congenital esotro-pia. Ophthalmology 90:132, 1983.

137. Ing MR: Botulinum alignment for congenital esotropia.Ophthalmology 100:318, 1993.

138. Ing MR: Outcome study of surgical alignment before sixmonths of age for congenital esotropia. Ophthalmology102:2041, 1995.

139. Ing M, Costenbader FD, Parks MM, Albert DG: Earlysurgery for congenital esotropia. Am J Ophthalmol61:1419, 1966.

140. Ingram RM, Walker C, Wilson JM, et al: A first attemptto prevent amblyopia and squint by spectacle correctionof abnormal refractions from age 1 year. Br J Ophthalmol69:851, 1985.

141. Irvine SR: Amblyopia ex anopsia. Trans Am OphthalmolSoc 46:527, 1948.

142. Jacobi KW: Das Verhalten der Netzhautkorrespondenzbei sekundarem Strabismus divergens. Klin MonatsblAugenheilkd. 154:193, 1969.

143. Jampolsky A: Differential diagnosis and management ofsmall degree esotropia and convergent fixation disparity.Am J Ophthalmol 41:825, 1956.

144. Jampolsky A: Bilateral anomalies of the oblique muscles.Trans Am Acad Ophthalmol Otolaryngol 61:689, 1957.

145. Jampolsky A, Noorden GK von, Spiritus M.: Chirurgieinutile pratiquee en cas d’esotropie refractive accommo-dative pure (letter). J Fr Ophtalmol 14:1, 1991.

146. Kaufmann H: Augenmuskeloperationen. In Kaufmann H,de Decker W, Friedburg D, et al, eds: Strabismus. Stutt-gart, Ferdinand Enke Verlag, 1995, p 634.

147. Kaufmann H, and Kolling HG: Ergebnisse der Fadenop-eration nach Cuppers. Klin Monatsbl Augenheilkd180:37, 1982.

148. Keenan JM, Willshaw HE: Outcome of strabismus sur-gery in congenital esotropia. Br J Ophthalmol 76:342,1992.

149. Keiner EC: Spontaneous recovery in microstrabismus.Ophthalmologica 177:280, 1978.

150. Kettesy A: Die Brille als Heilmittel des Schielens. KlinMonatsbl Augenheilkd 161:160, 1972.

151. Knapp P: Surgical orthophoria. In Arruga A, ed: Interna-tional Strabismus Symposium. University of Giessen,Germany 1966. Basel, S Karger 1968, p 302.

152. Knapp P: Personal communication, 1978.153. Kommerell G: Beziehung zwischen Strabismus und Nys-

tagmus. In Augenbewegungsstorungen, Neurophysiologieund Klinik. Munich, JF Bergmann, 1978, p 377.

154. Kommerell G: The pathophysiology of infantile strabis-mus. In Kaufmann H, ed: Transactions of the 16th Meet-ing of the European Strabismological Association, Gies-sen, Germany, 1987, p 47.

155. Kommerell G: The relationship between infantile strabis-mus and latent nystagmus. Eye 10:274, 1996.

156. Kommerell G, Mehdorn E: Is an optokinetic defect thecause of congenital nystagmus? In Lennerstrand G, ZeeDS, Keller EL, eds: Functional Basis of Ocular MotilityDisorders, Oxford, Pergamon Press, 1982, p 159.

157. Kommerell G, Ullrich D, Gilles U, Bach M: Asymmetryof motion VEP in infantile strabismus and in centralvestibular nystagmus. Doc Ophthalmol 89:373, 1995.

158. Krzystkowa K, Mirkiewicz-Sieradzka M: Niedowidzeniebez zesa. Klin Oczna 37:227, 1967.

159. Kushner BJ: Binocular field expansion in adults aftersurgery for esotropia. Arch Ophthalmol 112:639, 1994.

160. Kushner BJ, Morton GV: A randomized comparison ofsurgical procedures for essential infantile esotropia. AmJ Ophthalmol 98:50, 1984.

161. Kutluk S, Avilla CW, Noorden GK von: The prevalenceof dissociated vertical deviation in patients with sensoryheterotropia. Am J Ophthalmol 119:744, 1995.

162. Lam GC, Repka MX, Guyton DL: Timing of amblyopiatherapy relative to strabismus surgery. Ophthalmology100:1751, 1993.

163. Lang J: Uber die Amblyopie ohne Schielen und beiunauffalligem Schielwinkel. Ophthalmologica 141:429,1961.

164. Lang J: Die Bedeutung des primaren Mikrostrabismusfur die Entstehung des Schielens. Klin Montatsbl Augen-heilkd 151:352, 1967.

165. Lang J: Der kongenitale oder fruhkindliche Strabismus.Ophthalmologica 154:201, 1967.

166. Lang J: Evaluation in small angle strabismus or micro-tropia. In Arruga A, ed: International Strabismus sympo-sium, University of Giessen, Germany 1966. Basel, S.Karger, 1968, p 219.

167. Lang J: Squint dating from birth or with early onset.The First International Congress of Orthoptists. St Louis,Mosby–Year Book, 1968, p 231.

168. Lang J: Microtropia. Arch Ophthalmol 81:758, 1969.169. Lang J: Mikrostrabismus, ed 2. Bucherei des Augen-

arztes, No. 62. Stuttgart, Ferdinand Enke Verlag, 1982.170. Lang J: A new hypothesis on latent nystagmus and on

the congenital squint syndrome. Doc Ophthalmol 32:83,1982.

171. Lang J: Normosensorial late convergent strabismus. InCampos E, ed: Transactions of the Fifth Meeting of theInternational Strabismological Association (ISA), Rome,1986, p 536.

172. Lang J: Congenital or infantile, that is the question,Binocular Vision 3:116, 1988.

Esodeviations 353

173. Lang J: Historische und aktuelle Aspekte der Stereopsis(Goldmann Lecture). Klin Monatsbl Augenheilkd218:280, 2001.

174. Law FW: Squint operations and binocular function. TransAm Acad Ophthalmol Otolaryngol 58:546, 1954.

175. Leahey BD: Criteria for early surgical correction of con-comitant esotropia in infants and children. Trans AmAcad Ophthalmol Otolaryngol 58:106, 1960.

176. Leitch RJ, Burke JP, Strachan IM: Convergence excessesotropia treated surgically with fadenoperation and me-dial rectus muscle recessions. Br J Ophthalmol 74:278,1990.

177. Lewis A, Kline LB, Sharpe JA: Acquired esotropia dueto Arnold-Chiari I malformation. J Neuro Ophthalmol16:49, 1996

178. Lewis TL, Maurer D, Brent HP: Optokinetic nystagmusin children treated for bilateral cataracts. In Groner R,McConkie GW, Menz C, eds: Eye Movements and Hu-man Information Processing. Amsterdam, Elsevier, 1985,p 85.

179. Lobstein-Henry Y: Avantages et inconvenients du traite-ment chirurgical differe. Doc Ophthalmol 23:625, 1967.

180. Lyle TK: The time to operate. In First international Con-gress of Orthoptists. St Louis, Mosby–Year Book, 1968,p 129.

181. Lyle KT, Foley J: Subnormal binocular vision with spe-cial reference to peripheral fusion. Br J Ophthalmol39:474, 1959.

182. Magoon EH, Scott AB: Botulinum toxin chemotherapyin infants and children: An alternative to incisional stra-bismus surgery. J Pediatr Ophthalmol Strabismus110:119, 1987.

183. Mann I: The Development of the Human Eye. London,British Medical Association, 1949, p 274.

184. Marlow FW: Prolonged monocular occlusion as a test forthe muscle balance. Am J Ophthalmol 4:238, 1921.

185. Martens TG: Remarks on fixation disparity. Am OrthoptJ 20:68, 1970.

186. Mein J: The optokinetic nystagmus response in earlyonset strabismus. In Boschi MC, Frosini R, eds: Strabis-mus. Proceedings of the International Symposium onStrabismus, Florence, Italy, 1982, pp 21–23.

187. Meltzer U, Romem M: Nonaccommodative convergenceexcess. In Nemet P, Weiss JB, eds: International Sympo-sium on Strabismus and Amblyopia, Tel Aviv, 1985. ActaStrabologica CERES 31,

188. Meyer K, Breitschwerdt H, Kolling GH, Simonsz HJ:The early vs late infantile strabismus surgery study: Dosources for bias exist in this non-randomized trial? Br JOphthalmol 82:934, 1998.

189. Mohindra O, Zwaan J, Held R, et al: Development ofacuity and stereopsis in infants with esotropia. Ophthal-mology 92:691, 1985.

190. Molnar S: Some remarks on ‘‘antistrabismic preventiveaction’’ by Karpowicz on the ground of mass determina-tion of refractive power in prematures and babies, Szem-eszet 98:157, 1961. [Abstracted Am J Ophthalmol53:180, 1962.]

191. Moore S: The natural course of esotropia. Am Orthopt J21:80, 1971.

192. Muhlendyck H: Symptoms and treatment in hypoaccom-modation cases. In Nemet P, Weiss JB, eds: InternationalSymposium on Strabismus and Amblyopia, Tel Aviv,1985, Acta Strabologica, CERES 25.

193. Muhlendyck H: Reading disorders in the case of juvenileaccommodation disturbance. Presented at the 18th Con-ference of Reading and Reading Disorders, Rodin Reme-diation, Bern, August 26–29, 1991.

194. Muhlendyck H, Goerdt J: Effect of bifocals on accommo-dation rate in hypoaccommodatives, In Spiritus M, ed:

Transactions of the 22nd Meeting of the European Stra-bismological Association. Buren, The Netherlands, Aeo-lus Press, 1996, p 101.

195. Murray ADN, Calcutt C: The incidence of amblyopia inlongstanding untreated essential infantile esotropia. InCampos E, ed: Strabismus and Ocular Motility Disorders.London, Macmillan, 1990, p 45.

196. Naegele JR, Held R: The postnatal development of mon-ocular optokinetic nystagmus in infants. Vision Res22:341, 1982.

197. Nixon RB, Helveston EM, Miller K, et al: Incidence ofstrabismus in neonates. Am J Ophthalmol 100:798, 1985.

198. Noorden GK von: Mikrostrabismus. Wiss Z Karl-Marx-Universitat Leipzig 18:242, 1969.

199. Noorden GK von: The etiology and pathogenesis of fixa-tion anomalies in strabismus. Trans Am Ophthalmol Soc67:698 1969.

200. Noorden GK von: The etiology and pathogenesis of fixa-tion anomalies in strabismus. IV. Roles of suppressionscotoma and of motor factors. Am J Ophthalmol69:236, 1970.

201. Noorden GK von: Muscle surgery without scleral sutures.Ophthalmic Surg 13:113, 1982.

202. Noorden GK von: Tests of binocular function after sur-gery for essential infantile esotropia (letter). Can J Oph-thalmol 18:205, 1983.

203. Noorden GK von: Essential infantile esotropia: A contin-uing riddle (Richard C. Scobee Memorial Lecture). AmOrthopt J 34:52, 1984.

204. Noorden GK von: Round table conference: What do weinvestigate with the four-prism diopter test? In GregersenE, ed: Transactions of the European StrabismologicalAssociation, Copenhagen, 1984.

205. Noorden GK von: A reassessment of essential infantileesotropia (XLIV Edward Jackson Memorial Lecture). AmJ Ophthalmol 105:1, 1988.

206. Noorden GK von: Current concepts of essential infantileesotropia (Bowman Lecture). Eye 2:343, 1988.

207. Noorden GK von: Treatment of amblyopia and surgicaloutcome (letter). J Pediatr Ophthalmol Strabismus 35:5,1998.

208. Noorden GK von, Avilla CW: Nonaccommodative con-vergence excess. Am J Ophthalmol 101:70, 1986.

209. Noorden GK von, Avilla CW: Accommodative conver-gence in hypermetropia. Am J Ophthalmol 110:287,1990.

210. Noorden GK von, Avilla CW: Refractive accommodativeesotropia: A surgical problem? Int Ophthalmol 16:45,1992.

211. Noorden GK von, Frank JW: Relationship between am-blyopia and the angle of strabismus. Am Orthopt J26:31, 1976.

212. Noorden GK von, Helveston EM: Strabismus: A Deci-sion Making Approach. St Louis, Mosby–Year Book,1994, p 95.

213. Noorden GK von, Jenkins RH: Accommodative ampli-tude in children wearing bifocals. In Lennerstrand G, ed:Transactions of the Sixth Meeting of the InternationalStrabismological Association, Vancouver, 1994. Boca Ra-ton, FL, CRC Press, 1995, p 201.

214. Noorden GK von, Munoz M: Recurrent esotropia. J Pedi-atr Ophthalmol Strabismus 25:275–279, 1988.

215. Noorden GK von, Brown DJ, Parks MM: Associatedconvergence and accommodative insufficiency. Doc Oph-thalmol 34:393, 1973.

216. Noorden GK von, Isaza A, Parks MM: Surgical treatmentof congenital esotropia. Trans Am Acad Ophthalmol Oto-laryngol 76:1465, 1972.

217. Noorden GK von, Morris J, Edelman P: Efficacy ofbifocals in the treatment of accommodative esotropia.Am J Ophthalmol 85:830, 1978.


218. Noorden GK von, Munoz M, Wong S: Compensatorymechanisms in congenital nystagmus. Am J Ophthalmol104:387, 1987.

219. Norcia AM: Abnormal motion processing and binocular-ity: Infantile esotropia as a model system for effects ofearly interruptions of binocularity. Eye 10:259, 1996.

220. Norcia AM, Garcia H, Humphry R, et al: Anomalousmotion VEPs in infants and in infantile esotropia. InvestOphthalmol Vis Sci 32:436, 1991.

221. Ogle K N, Mussey F, Prangen A de H: Fixation disparityand fusional processes in binocular single vision. Am JOphthalmol 32:1069, 1949.

222. Ohtsuki H, Hasebe S, Kobashi R, et al: Critical period forrestoration of normal stereoacuity in acute-onset comitantesotropia. Am J Ophthalmol 118:502 1994.

223. Parks M M: Abnormal accommodative convergence insquint. Arch Ophthalmol 59:364, 1958.

224. Parks M M: Second thoughts about the pathophysiologyof monofixational phoria. Am Orthopt J 14:159, 1964.

225. Parks M M: Summary and conclusion. Symposium: Es-sential infantile esotropia. Am Orthopt J 18:19, 1968.

226. Parks M M: Stereo-acuity as an indicator of bifixation.In Arruga A, ed: International Strabismus Symposium,University of Giessen, Germany 1966. Basel, S Karger,1968, p 258.

227. Parks M M: The monofixational syndrome. Trans AmOphthalmol Soc 67:609, 1969.

228. Parks M M: Discussion of paper by Noorden GK von,Isaza A, Parks M M: Surgical treatment of congenitalesotropia. Trans Am Acad Ophthalmol Otolaryngol76:1465, 1972.

229. Parks M M: Ocular Motility and Strabismus. Hagerstown,MD, Harper & Row, 1975.

230. Parks M M: Congenital esotropia with a bifixation result.Report of a case. Doc Ophthalmol 58:109, 1984.

231. Parks M M: Congenital esotropia vs. essential infantileesotropia. Graefes Arch Clin Exp Ophthalmol 226:106,1988.

232. Parks M M: Stereopis in congenital esotropia. Am Or-thopt J 47:99, 1997.

233. Parks M M, Eustis A T: Monofixational phoria. AmOrthopt J 11:38, 1961.

234. Perterseim M M W, Bickley E: Medial rectus fadenopera-tion for esotropia only at near fixation. J Am AssocPediatr Ophthalmol Strabismus 1:129, 1997.

235. Passo M, Shults W T, Talbot T, Palmer E A: Acquiredesotropia—a manifestation of Chiari I malformation. JClin Neuro Ophthalmol 4:151, 1984.

236. Pickering J D, Simon J W, Ratliff D D, et al: Alignmentsuccess following medical rectus recessions in normaland delayed children. J Pediatr Ophthalmol Strabismus32:225, 1995.

237. Pollard Z F: Accommodative esotropia during the firstyear of life. Arch Ophthalmol 94:1912, 1976.

238. Pollard Z F: Accommodative esotropia after ocular andhead injury. Am J Ophthalmol 109:195, 1990.

239. Prieto-Diaz J: Large bilateral medical rectus recession inearly esotropia with bilateral limitation of abduction. JPediatr Ophthalmol Strabismus 17:101, 1980.

240. Prieto-Diaz J: Five year follow-up of ‘‘large’’ (6–9)bimedial recession in the management of early onset,essential infantile esotropia with Ciancia syndrome. Bin-ocular Vision 1:209, 1985.

241. Prieto-Diaz J, Prieto-Diaz I: Long term outcome oftreated congenital/infantile esotropia: Does early surgicalbinocular alignment restoring subnormal binocular visionguarantee stability? Binocular Vision Strabismus Q13:249, 1998.

242. Pugh MA: Squint Training. New York, Oxford UniversityPress, 1936, p 81.

243. Raab EL: Etiologic factors in accommodative esotropia.Trans Am Ophthalmol Soc 80:657, 1982.

244. Rethy I: Neue Prinzipien in der Behandlung von 1⁄2 bis 3jahrigen Schielkindern. Ophthalmologica 157:285, 1969.

245. Rethy I, Gal Z: Results and principles of a new methodof optical correction of hypermetropia in cases of esotro-pia. Acta Ophthalmol 46:757, 1968.

246. Reed MJ, Steinbach MJ, Anstis SM, et al: The develop-ment of optokinetic nystagmus in strabismic and monocu-larly enucleated subjects. Behav Brain Res 46:31, 1991.

247. Richter S: Untersuchugen uber die Hereditat des Strabis-mus concomitans. Leipzig, VEB Georg Thieme, 1967.

248. Rogers GL, Bremer DL, Leguire LE, Fellows R R: Clini-cal assessment of visual function in the young child. Aprospective study of binocular vision. J Pediatr Ophthal-mol Strabismus 23:233, 1986.

249. Rogers G L, Chazan S, Fellows R, Tsou B H: Strabismussurgery and its effect upon infant development in congen-ital esotropia. Ophthalmology 89:479, 1982.

250. Romano P E: Strabismus surgery dosage and timing;outcomes:microtropias and minitropias; sterotests forscreening (editorial). Binocul Strabismus Q 15:207, 2000.

251. Round table discussion on the long-term significance ofsensory anomalies of squint. In Strabismus ’69; Transac-tions of the Consilium Europaeum Strabismi Studio Dedi-tum Congress, London, 1969. St Louis, Mosby–YearBook, 1970.

252. Santori M: Influenza della ipercorrezione chirurgica diuno strabismo convergente sulle condizioni della corris-pondenza retinica. Ann Ottalmol 91:480, 1965.

253. Schiavi C, Bellusci C, Gasparrini E, Campos E: Prognos-tic value of primary inferior oblique muscles overactionin refractive accommodative esotropia. In LennerstrandG, ed: Advances in Strabismology. Buren, The Nether-lands, Aeolus Press, 1999, p 339.

254. Scobee RG: The Oculorotary Muscles, ed 2. St Louis,Mosby–Year Book, 1952.

255. Scott AB, Magoon EH, McNeer KW, Stager DR: Botuli-num treatment of childhood strabismus. Ophthalmology97:1434, 1990.

256. Setayesh AR, Khodadoust AA, Daryani SM: Microtropia.Arch Ophthalmol 96:1842, 1978.

257. Shallo-Hoffmann J, Faldon M, Hague S, et al: Motiondetection deficits in infantile esotropia without nystag-mus. Invest Ophthalmol Vis Sci 38:219, 1997

258. Shauly Y, Miller M, Meyer E: Clinical characteristicsand long-term postoperative results of infantile esotropiaand myopia. J Pediatr Ophthalmol Strabismus 34:357,1997.

259. Shauly Y, Prager TC, Mazow ML: Clinical characteristicsand long-term postoperative results of essential infantileesotropia. Am J Ophthalmol 117:183, 1994.

260. Shippman S, Cohen KR: Relationship of heterophoria tostereopsis. Arch Ophthalmol 101:609, 1983.

261. Sidikaro Y, Noorden GK von: Observations in sensoryheterotropia. J Pediatr Ophthalmol Strabismus 19:12,1982.

262. Simon AL, Borchert M: Etiology and prognosis of acute,late-onset esotropia. Ophthalmology 104:1348, 1997.

263. Simon JW, Waldman JB, Courture KC: Cerebellar astro-cytoma manifesting as isolated, comitant esotropia inchildhood. Am J Ophthalmol 121:584, 1996.

264. Smith MD, Baker JD: Esotropia as the presenting signof brain tumor. Am Orthopt J 40:72, 1990.

265. Sondhi N, Archer SM, Helveston EM: Development ofnormal ocular alignment. J Pediatr Ophthalmol Strabis-mus 25:210, 1988.

266. Spielmann A: Adduction, latent nystagmus, infantile stra-bismus and the opto-motor syndrome of congenital uni-ocular organic amblyopia. In Kaufmann H, ed: Transac-

Esodeviations 355

tions of the 16th Meeting of the European Strabismologi-cal Association, Giessen, Germany, 1987, p 291.

267. Spielmann A: Les soi-disant syndromes de blocage: Eso-deviation, elevation, et adduction dans les strabismesprecoces (ou le syndrome opto-moteur des monophtalmescongenitaux). Presented at Societe francaise ophtalmolo-gie meeting, May 1987.

268. Spielmann A: Les soi-disant syndromes de blocage: Ad-duction, esodeviation et elevation dans les strabismesprecoces. Ophtalmologie 2:1, 1988.

269. Spielmann A, Spielmann AC: Idees recues et erreursd’interpretation des signes cliniques chez le nourrissonstrabique. Ophtalmologie 8:42, 1994.

270. Spiritus M: In Controverses et concepts inhabituels dansle traitement chrirurgical des strabismes, Perpignan,France, 1991, p 135.

271. Sprunger DT, Wassermann B, Stidham DB: The relation-ship between nystagmus and surgical outcome in congen-ital esotropia. J Am Assoc Pediatr Ophthalmol Strabis-mus 4:21, 2000.

272. Stark N, Vanselow K, Stahl E, Zuncov AA: Behandlungder Esotropie mit akkommodativem und nichtakkommo-dativem Konvergenzexzess. Fadenoperation mit beidsei-tiger Rucklagerung. Klin Monatsbl Augenheik 96:513,1999.

273. Stangler E: Das Nachbildverhalten bei Heterophorie. KlinMonatsbl Augenheilkd 160:207, 1972.

274. Stangler-Zuschrott E: Strabismus convergens bei hoher-gradiger Hypermetropie. Klin Monatsbl Augenheilkd167:469, 1975.

275. Steffen H, Auffahrt GU, Kolling GH: Posterior fixationsuture and convergence excess esotropia. Strabismus6:117, 1998.

276. Struck MC, Ver Hoeuve J, France T: Binocular corticalinteraction in the monofixational syndrome. J PediatrOphthalmol Strabismus 33:291, 1996.

277. Stumpf F: Is early surgery really necessary? In Mein J,Bierlaagh JJM, Brummelkamp-Dons TEA, eds: Or-thoptics: Proceedings of the Second International Or-thoptic Congress. Amserdam, Exerpta Medica, 1971, p220.

278. Swan KC: Esotropia following occlusion. Arch Ophthal-mol 37:444, 1947.

279. Taylor DM: How early is early surgery in the manage-ment of strabismus? Arch Ophthalmol 70:752, 1963.

280. Taylor DM: Congenital strabismus: The common senseapproach. Arch Ophthalmol 77:478, 1967.

281. Taylor DM: Is congenital esotropia functionally curable?Trans Am Ophthalmol Soc 70:529, 1972.

282. Taylor DM: Congenital Esotropia. Management andPrognosis. New York, Intercontinental Medical Book,1973, pp 14, 87, 89.

283. Taylor RH, Armitage IM, Burke JP: Fully accommoda-tive esotropia in adolescence. Br Orthopt J 52:25, 1995.

284. The fourth monitoring report of the early vs. late infantilestrabismus surgery study group. Strabismus 5:133, 1997.

285. Thorn F, Gwiazda J, Cruz AAV, et al. The developmentof eye alignment, convergence, and sensory binocularityin young infants. Invest Ophthalmol Vis Sci 35:544,1994.

286. Tillson G, Pratt-Johnson JA: Fusion loss from longstand-ing unilateral cataracts in adults. In Lenk-Schafer M, ed:Orthoptic Horizons. Transactions of the Sixth Interna-tional Orthoptic Congress, Harrogate, England, LIPS,1987, p 327.

287. Travers TAB: The practical importance of abnormal reti-nal correspondence. Trans Am Acad Ophthalmol Otola-ryngol 54:561, 1950.

288. Tychsen L: Visual cortex maldevelopment as a cause ofesotropic strabismus (letter). Arch Ophthalmol 105:457,1987.

289. Tychsen L, Lisberger SG: Maldevelopment of visual mo-tion processing in humans who had strabismus with onsetin infancy. J Neurosci 6:2495, 1986.

290. Tychsen L, Hurtig RR, Scott WE: Pursuit is impaired butthe vestibulo-ocular reflex is normal in infantile strabis-mus. Arch Ophthalmol 103:536, 1985.

291. Vasquez R, Calhoun JH, Harley RD: Development ofmonofixation syndrome in congenital esotropia. J PediatrOphthalmol Strabismus 18:42, 1981.

292. Veronneau-Troutman S: Fresnel prism membrane in thetreatment of strabismus. Can J Ophthalmol 6:249, 1971.

293. Vollrath-Junger C, Lang J: Akuter Strabismus convergensbei erhohtem Hirndruck. Klin Monatsbl Augenheilkd190:359, 1987.

294. Weakley DR, Holland DR: Effect of ongoing treatmentof amblyopia on surgical treatment in esotropia. J PediatrOphthalmol Strabismus 34:275, 1997.

295. Weakley DR, Stager DR, Everett ME: Seven-millimeterbilateral medial rectus recessions in essential infantileesotropia. J Pediatr Ophthalmol Strabismus 28:113, 1991.

296. Webster’s Ninth New College Dictionary, Springfield,MA, Merriam-Webster, 1985, p 276.

297. Weeks CL, Hamed LM: Treatment of acute comitantesotropia in Chiari I malformation. Ophthalmology106:2368, 1999.

298. Westfall CA, Eizenman M, Kraft SP, et al: Cortical binoc-ularity and monocular optokinetic asymmetry in early-onset esotropia. Invest Ophthalmol Vis Sci 39:1352,1998.

299. Williams AS, Hoyt CS: Acute comitant esotropia in chil-dren with brain tumors. Arch Ophthalmol 107:376, 1989.

300. Windsor CE: Surgically overcorrected esotropia: A studyof its cause, sensory anomalies, fusional results, andmanagement. Am Orthopt J 16:8, 1966.

301. Worth C, cited in Chavasse FB: Worth’s squint or thebinocular reflexes and the treatment of strabismus, ed 7.London, Bailliere, Tindall & Cox, 1939 p 289.

302. Worthan E, Greenwald MJ: Expanded binocular periph-eral visual fields following surgery for esotropia. J PediatrOphthalmol Strabismus 26:109, 1989.

303. Wright KW, Edelman PM, McVey JH, et al: High-gradestereo acuity after early surgery for congenital esotropia.Arch Ophthalmol 112:913, 1994.

304. Wybar K: The significance of squint in certain forms ofmalignant disease. Br Orthopt J 24:47, 1967.

305. Zak TA, Morin JD: Early surgery for essential infantileesotropia: Results and influence of age upon results. CanJ Ophthalmol 17:213, 1983.

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