RELATIONSHIP OF BASAL IRIDECTOMY TO SHALLOW ...

RELATIONSHIP OF BASAL IRIDECTOMY TOSHALLOW CHAMBER FOLLOWING

CATARACT EXTRACTION

BY Kenneth C. Swan, M.D.*

A STUDY CONDUCTED at the University of Oregon Medical School since1950 revealed that shallowing of the anterior chamber after cataractextraction was an uncommon, but sometimes serious, complicationwhich developed under several circumstances. In patients observedprior to 1951, the anterior chamber occasionally did not reform duringthe first twenty-four hours after surgery. In those eyes a wound leakusually was demonstrable. In 1951, we began to use a limbus-basedflap of conjunctiva and Tenon's capsule to bury a half-lap type oflimbal incision which had been closed with multiple catgut sutures(Figure 1). This technique virtually eliminated failure of reformationof the anterior chamber and epithelial ingrowth,' but it did notprevent a second type of shallow chamber which most commonlydeveloped without a demonstrable wound leak seven to twenty-onedays postoperatively. In 1957, Weisel and 12 described what wethought were the important clinical features of this second type ofshallow anterior chamber (Table 1). It was associated with hypotony,choroidal separation, posterior vitreous detachment with forward dis-placement, and adherence of an intact vitreous face to the pupil andiris opening. The resultant vitreous obstruction to the flow of aqueousfrom the posterior into the anterior chamber contributed to theshallow chamber. This viewpoint was not widely accepted becausethe prevalent concept then was that pupillary obstruction wouldhave to be associated with elevated tension. We felt that, in those eyes,there was hypotony, rather than glaucoma, because the formation ofaqueous wvas decreased. Chandler and Maumenee have providedevidence to stupport this concept.:'

*Froimi the Tolhn E Weeks Inistittute of Ophthalmology, University of OregonMedical School.TR. AM. OP1ITH. Soc., vol. 60, 1962

Kenneth C. Swan

FIGURE 1

The half-lap type of limbal incision is begun perpendicular to the surface at thejunction of opaque sclera and translucent limbal stroma. Halfway through thestroma, it is split forward and then extended to enter the anterior chamber nearSchwalbe's line. The limbal incision is closed by multiple absorbable sutures

buried under a limbus-based flap.

TABLE 1. MAJOR TYPES OF SHALLOW CHAMBER AFTER CATARACT EXTRACTION

(1) Delayed reformation-wound leak generally demonstrable(2) Late shallowing of chamber (4-21 days) wound leak seldom demonstrable

(a) Onset 4-21 days after surgery(b) Gross detachment of choroid and ciliary body(c) Hypotony(d) Forward displacement of intact vitreous face with obstruction of pupil and

iris coloboma

In some, but not all, of our cases of late shallow chamber withoutdemonstrable wound leak, the anterior chamber reformed spon-taneously, a phenomenon which could not be depended upon, butwhich made the evaluation of therapy difficult. We did find thatintensive use of mydriatics sometimes alternated with miotics generallyrestored the anterior chamber if initiated before adherence of the

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Shallow Chamber Following Cataract Extraction

FIGURE 2

Stereophotographs illustrating mydriatic treatment of shallow chamber withvitreous obstruction, hypotony, and choroidal detachment of three days' duration(top). The chamber has begun to deepen after 40 minutes (middle) and is deep

with maximal mydriasis at 90 minutes (bottom).

vitreous face to the iris became too firm. The effectiveness of thisprocedure has been confirmed by Chandler.4 In this eye (Figure 2),photographed twelve days after a seemingly uncomplicated intra-capsular extraction, a shallow chamber developed and persisted forthree days. The anterior chamber reformed within ninety minutesafter the topical administration of single drops of 1 per cent atropinesulfate, 5 per cent cocaine, and 1 per cent epinephrine bitartrate.Another non-sturgical measure was effective in some neglected

caises; this was to rupture pupillary adhesions to the vitreous face bygentle point pressuire applied to the iris through the anesthetizedcornea. The maneuver was performed at the slit-lamp biomicroscope,

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or with the operating microscope, if the patient was lying down be-cause magnification was desirable for visual control and observationof the results. Only topical anesthesia was required and no speculumwas necessary. The lubricated tip of a glass rod was placed on thecornea midway between the pupillary margin and the limbus (Figure3). Only gentle pressure indented the cornea and iris in those softeyes. Often pupillary adhesions were seen to separate and the anteriorchamber to reform within two to three minutes. NMy colleagues andI did not use the technique until at least eight days postoperatively,but noted no wound separations or other ill effects from the manetver.

FIGURE 3. IECHANICAL RIUPTURE OF IRIS ADHESIONS TO VITREOUS AT THE PUPILLARY

MARGIN.

With topical anesthesia the cornea aind underlyillg iris arc ectly indented witlh thclubricated tip of al glass ro(l.

Shallow chamber associated wvith vitreotus block, lhypotoni, andchoroidal detachment often is aI precursor to aphakic glaucomaassociated with vitreous herniation and pupillarv obstruction. There-fore, it seemed logical to treat this type of shallow chamber alongthe same principles; that is, in both conditions, attempts were madeto relieve the vitreous obstruction of the pupil and iris coloboma.(Table 2). If the anterior chamber could not be reformed by drugsor massage through the cornea, peripheral iridectomy was performedin the inferior temporal quadrant (Figure 4), rather tlhain wait Unltilextensive peripheral adlhesions or vitreous block glaucoma had de-veloped!5 Without evidence of continuous external leakage of aqueous,I did not deem it necessary to open the conjunctival and Tenon's

216 Kenneth C. Swait


TABLE 2. ORDER OF TREATMENT OF SHALLOW CHAMBER WITHOUT DEMONSTRABLEWOUND LEAK

(1) MedicalIntensive mydriatic therapy sometimes alternated with miotics to mobilize the

pupil(2) Mechanical

Point pressure on iris throuLgh cornea to mechanically disrupt iris adhesions tovitreous face

(3) Surgical1. Peripheral iridectomy2. Other surgical procedures, rupture vitreous face, sclerotomy

FIGURE 4. INFERIOR TEMPORAL IRIDECTOMY FOR RELIEF OF VITREOUS OBSTRUCTIONOF PUPIL AND OPERATIVE COLOBOMA.

incision and explore the limbal wound. In our cases, leakage ofaqueous under the conjunctiva did not appear significant. RobertCowger and 16 reviewed our cases of unintentional filtrations whichdeveloped after cataract extraction (Figure 5). No correlation couldbe found between the occurrence of filtrations and shallow chambers.

I reviewed over 3,000 cataract extractions which were performed onthe services at the University of Oregon Medical School in the periodfrom 1951 through 1961. During that period, peripheral iridectomywas performed on six eyes with postoperative shallow chambersassociated with hypotony; three of these patients had not kept out-patient appointments after their discharge from the hospital and,

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Kenneth C. Swan

FIGURE 5. UNINTENTIONAL FILTRATION WHICH DEVELOPED AFTER CATARACT

EXTRACTION.

No correlation could be found between the occurrence of this type of filtrationand the incidence of postoperative shallow chamber.

therefore, were not under control of the attending physicians forperiods which allowed firm adhesions to develop between the vitreousface and iris. A fourth patient had a low grade uveitis and the fifthand sixth patients had had small hyphemias. Posterior synechias madeit impossible for us to mobilize the pupil by non-surgical means. Inall six eyes, lasting restoration of the anterior chamber was obtainedby iridectomy alone. In addition, iridotomy was performed throughlimbal puncture wounds on two other eyes with shallow chambers,choroidal detachment, and hypotony. One of the iridotomies closedwith recurrence of the shallow chamber, but a subsequent peripheraliridectomy was effective. In summary, restoration of the anteriorchamber was obtained by iridectomy or iridotomy in all eight eyeswithout resorting to air injections, rupture of the vitreous, sclerotomy,or resuturing of the limbal wound. Two other patients were not in-cluded in this series because the surgeons ruptured the vitreous facewhen they attempted to separate the pupillary margins from thevitreous with a spatula. The chamber was restored in these cases;

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Shallow Chamber Followving Cataract Extraction

however, in one, there was bleeding into the vitreous with resultantreduction in visual acuity due to residual vitreous opacities and, inthe other, the cosmetic result was poor due to tearing of the peri-pheral iris. As a result of these experiences coupled with the demon-strated effectiveness of iridectomy alone, attempts to free the pupilfrom the vitreous face were considered unnecessary and apt to addcomplications.During the same period from 1951 through 1961, there were

observed on our services only six eyes with glaucoma associated withobstruction of the primary aqueous circulation by clear vitreous.Cases of pupillary obstruction due to organized hemorrhage, inflam-matory membranes, or lens remnants were not included in this series,although a number were observed. This relatively low incidence ofvitreous block glaucoma verified Chandler's belief that this type ofglaucoma was largely preventable. In addition to the six cases fromour services, two other patients were referred for care by other sur-geons. Of the eight patients, three had had round pupil extractionswith peripheral iridectomy; one had had a round pupil extractionwith iridotomy; and the three others had had what were thoughtto be complete iridectomies, but the openings did not extend to theroot of the iris. The eighth case had a radial iridotomy which did notextend to the base of the iris (Figure 6). In all eight, the iriscolobomas as well as the pupils were obstructed by vitreous.The results of treatment of the eight cases of vitreous block glau-

coma are summarized in Table 3. None responded to mydriatictherapy alone, but point pressure on the iris through the cornea wasdramatically effective in one. In the other seven eyes, peripheraliridectomy was made. In five, the anterior chamber reformed promptlyand lasting relief of the glaucoma was obtained without disruptionof the vitreous face. In the sixth case, increased ocular tension andshallowing of the anterior chamber recurred within twenty-four hours.A second iridectomy with deliberate rupture of the vitreous face wassuccessful. In the seventh case, the iridectomy was noted to becomeobstructed by vitreous, while the patient was still on the operatingtable. No appreciable deepening of the anterior chamber occurredin the ten to fifteen minutes after iridectomy and the globe remainedrelatively firm; therefore, the vitreous face was deliberately openedthrough the iridectomy. At first, viscid vitreous, and then wateryfluid escaped. An anterior chamber developed promptly and theglaucoma was controlled. In the last two cases, I could not be certainwhether the obstruction was at the point of contact of the vitreous

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Kenneth C. Swan

FIGURE 6

Intracapstular cataract extraction with radial iridotomv 6 weeks after sturgery byresident physician (top, left). Gonioscopy revealed that coloboma did not extendto periphery of the iris and vitreous was herniating into it (bottom). Actute vitreotus

block glaucomiia developed two weeks later (top, right).

witlh the iris, or by the vitreous face with posterior flow of aqueous,as postulated by Leonard Christensen and Robert Shaffer.7 These twocases, and observations that the iris coloboma as well as the pupil badto be plugged by forward displacement of the vitreous face to pro-duce either shallow chamber with hypotony, or shallow chamberwith glaucoma, led us to change our terminology from "pupillary blockglaucoma" to the more accurate designation of "vitreous blockglaucoma." I observed hundreds of eyes in which the pupil appeared

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Shallow Chamber Following Cataract Extraction2

to be completely obstructed by the herniation of the intact vitreousface, but neither shallow chamber nor vitreous block glaucoma de-veloped as long as some part of the iris coloboma was open. Thisdirected our attention to the relationship of the vitreous to the peri-pheral iris in aphakia.

TABLE 3. EIGHT CASES OF VITREOUS BLOCK GLAUCOMA

(1) None cured by mydriatics(2) One cured by mydriatics plus point pressure through cornea(3) Five cured by peripheral iridectomy(4) Two cured by peripheral iridectomy plus rupture of vitreouis face

Beginning in 1955, the position of the vitreous face in relation tothe peripheral iris and the wound of entry into the eye was studied byslit-lamp biomicroscopy and gonioscopy in all aphakic eyes observedin our clinic. The anterior face of the vitreous generally was found tobe quite convex with the apex in the pupillary area; therefore, ad-herence of the vitreous seldom occurred to incisions entering the globeat Schwalbe's line. In uncomplicated intracapsular extractions, hernia-tions of the intact vitreous face through the periphery of the iriscolobomas seldom were seen provided that a relatively basal openingwas present, but herniations through the pupil were found to be re-latively common.

In the first months after intracapsular cataract extraction, thevitreous face, as observed with a gonioscope through the operativecoloboma, seldom was in contact with the back surface of the peri-pheral one-third of the iris, but often was in contact with the irisin the pupillary area (Figure 7). This observation was confirmedby the study of aphakic eyes in the John E. Weeks Laboratory and inpublished microphotographs. In most eyes, the protrusion of ciliaryprocesses into the eye make it impossible for the intact vitreous faceto contact the extreme periphery of the iris; consequently, a posteriorchamber usually persists in aphakic eyes (Figure 8). Persistence ofa peripheral posterior chamber explains why it usually is possible toperform peripheral iridectomy in aphakic eyes without loss of vitreous;also, it seemed logical that in the conduct of cataract surgery an irisopening in the periphery would be less apt to be plugged by forwardherniation of the vitreous than an opening placed close to thesphincter. Clinical observation proved this to be the case. What is theclinical importance of this anatomical fact?

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Kenneth C. Swan

FIGURE 7

After uncomplicated cataract extraction the vitreous face is most prominent in thepupillary area and often herniates through it. In the periphery the vitreous usually

is behind the level of the iris and not in contact with it.

FIGURE 8. PERSISTENCE OF POSTERIOR CHAMBER IN PERIPHERY OF APHAKIC EYEOBTAINED POST MORTEM.

The ciliary body and processes prevent the vitreous from contacting the extremeperiphery of the iris.

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Last year, in a paper presented before this Society, Chandler ex-pressed the belief that vitreous block glaucoma was more commonwith round pupils than with complete iridectomy.4 John McLean didnot agree. Gonioscopic studies conducted at Oregon may resolve thisargument. No significant difference was found in the incidence ofshallow chamber with later vitreous block glaucoma, in cases withperipheral versus complete iridectomy, provided that an adequateopening was obtained in the extreme periphery of the iris.

Postoperative gonioscopy was performed in nearly 2,000 aphakiceyes; these studies revealed that in one out of every four casesoperated by our resident staff what had been intended to be a com-plete iridectomy often did not extend to within one millimeter of theroot of the iris; however, one out of three peripheral iridectomie3was not basal. This higher incidence of inadequate openings in theperiphery of the iris accounted for what at first seemed to be a higherincidence of shallow chambers developing after our round pupilextractions. The incidence of delayed shallow chamber (with evidenceof vitreous b!ock and without demonstrable wound leak) was 5 percent (29 out of 585 eyes), without an adequate peripheral iris opening,as compared to slightly less than 2 per cent (27 in 1412 eyes) in whichthe iris opening extended within one millimeter of the iris root(Table 4).

TABLE 4. INCIDENCE OF SHALLOW CHAMBERIN RELATION TO IRIS OPENING

5.1% without adequate basal opening(29 in 581 eyes)

1.9% with adequate basal opening(27 in 1412 eyes)

It was evident from the above described studies that an inadequateperipheral iris opening could not be the sole cause of shallowchamber due to vitreous obstruction, but actually was an importantfactor. There were noteworthy clinical examples which could bedocumented by photography. Figure 9 shows the eyes of a patientwho developed a vitreous type block glaucoma six weeks aftercataract extraction. The surgeon thought that he had performed acomplete iridectomy, but it can be seen that the iridectomy did notextend to the base of the iris. Peripheral iridectomy inferiorly re-lieved the shallow chamber and glaucoma. Cataract extraction witha complete iridectomy extending to the root of the iris was performedon the other eye without complications. The eye of another patientwho developed vitreous block glaucoma was photographed through

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Kenneth C. Swan

FIGURE 9

Intracapsular cataract extraction O.D. (left) was followed by glaucoma. Theinitial iridectomy did not extend to the base of the iris and was blocked byvitreous. The glaucoma was cured by iridectomy in the inferior temporal periphery.Course of O.S. (right) was uncomplicated because the iridectomy extended

peripheral to forward curve of vitreous face.

FIGURE 10

"Complete" iridectomy viewed through the front surface (center) of an Allen-Thorpe gonioscope appears adequate, but the lower mirror reveals that the

iridectomy did not extend to the periphery.

224'1%

:..,

iii.s


an Allen-Thorpe gonioscope (Figure 10). In a direct view throughthe flat front surface of the lens, a complete iridectomy of adequatesize appears to have been made, but it can be seen in the lowermirror that the iridectomy did not extend to the base of the iris.The intact vitreous face blocked both the pupil and the coloboma!An inferior peripheral iridectomy was effective.

These clinical and anatomical studies led to a review of our tech-niques of iris openings in relation to the incision. On my servicessince 1951, all cataract operations have been performed with a half-lap type of incision (Figure 1), but some other members of thefaculty have continued to use keratome and scissors. In both tech-niques, we observed that it was difficult to obtain an adequateperipheral opening in the iris if the incision entered the anteriorchamber forward in the cornea; this was dramatically demonstratedin microscopic studies of the eye of a patient who died nine days afteran intracapsular cataract extraction performed by a resident surgeon.At death, the patient had a shallow anterior chamber with choroidal

>'YVitreous face

FIGURE 11. POSTMIORTENM SPECIMEN OBTAINED 11 DAYS AFTER CATARACT EXTRAC-TION, COMPILICATEJ) B'Y SHALLOW CHAMBER, HYPOTONY, AND CHOROIDAL

1)ETACHMENT.Inicision entered the anterior chaimiber too far forward, and the iridectomy was notbasal. Vitreous was adherent to edge of coloboma and pupil, with resultant

obstruction of aqueous flow. Wound separated by trauma of enucleation.

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Kentneth C. Swani

detachment and forward herniation of the vitreous. A wound leakwas not demonstrable clinically or by inspection of the wound postmortem. Unfortunately the half-lap incision was separated by thetrauma of enucleation. As shown in Figure 11, the surgeon excisediris only back to the point of entry of the incision into the eye. As theincision entered the anterior chamber well forward in the cornea theiridectomy was not basal. Vitreous was adherent to the iris only nearthe edge of the pupillary margin and a posterior chamber was present.A more basal iridectomy in this eye would have been less likely tohave been blocked by the vitreous face which was well away from theiris periphery. The importance of a basal iridectomy was illustratedin another eye enucleated with the vitreous block type of glaucoma(Figure 12). Again, it can be seen that a basal iridectomy had notbeen made. The vitreous was adherent only to the edge of the opera-tive coloboma. Again, a peripheral posterior chamber was presentand the vitreous was well away from the periphery of the iris. In thiseye also a more basal iridectomy would have had less chance tobecome obstructed.

FIGURE 12. VTITIkEOIJS BILO(CK CGIAUC(OMA RlSULTING FROAI INAI)EQUATF I Ff1 IP-IE Al,IBAIS OPENING.

The vitreouLs was a(ldherent to the edges of the ptipil anid the colohoina, but atposterior chamber was preseint. The ciliary body aind processes might have

prevented the vitreous from blocking a peripheral iris opening.

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Shallow Chalmalber Following Catar-act ExttactionWhat lessons did we learn about the technique of iridectomy in

cataract extraction? First, we learned that an incision entering theanterior chamber in the region of Schwalbe's line permitted an ade-quate opening to be made in the peripheral iris and that suich anincision was less apt to be obstructed by either iris or vitreous thana corneal incision. Figure 13 illustrates a patient with a corneal in-cision who was referred to me with vitreous block type of glaucoma.Both iris and vitreous were adherent to the corneal iincision. Theiridectomy which relieved the glaucoma and shallow chamber canl beseen inferiorly. A new pupil was created later by photocoagulation.

In the performance of a complete iridectomy, our resident staff hasbeen instructed to grasp the iris just behind the sphincter, ratherthan at the sphincter, as is advised in many surgical textbooks. Ifthe iris is grasped behind the sphincter, the peripheral iris is stretchedinto the wound and can be excised, whereas if the iris sphincter onlyis grasped, the peripheral iris is relaxed an(d may not be drawn intothe incision. An inadequate peripheral opening may result as shown

FIGURE 13. ADHERENCE OF IRIS AND VITREOUS TO A CORNEAI. INCISION FOR CATARACT

EXTRACTION.

The smllall updrawn puipil lecallle obstructed by vitreous. The resultanlt ,l.4aucomawas cured by the peripheral iridectomy made inferiorly.

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Kenneth C. Swan

in Figure 10. I do not advocate tearing of iris (iridodialysis) becausethere is danger of inducing serious bleeding.

Simple iridotomies are no longer performed intentionally on myservices. The custom used by some surgeons of introducing the scissors'tips into the anterior chamber to snip the iris almost invariably leavesan opening which is relatively small and too far from the base of theiris (Figure 14). This is particularly apt to occur if the pupil has beenwidely dilated to facilitate delivery of the lens. To perform an adequate

FIGURE 14. UNDESIRABLE TYPE OF IRIDOTONIY RESULTS WHEN SCISSORS ARE

INTROI)UCED INTO THE EYE AND THE IRIS IS SNIPPED WITHOUT THE USE OF FORCEPS.

The opening is small and not in the periphery. It is apt to be plugged by thevitreous forward curve of the face.

peripheral iridectomy, forceps should be used to grasp the extremeperiphery of the iris. I have observed that radial iridotomies orsphincterotomies advocated by some surgeons to reduce the size of thecoloboma are particularly apt to be plugged by vitreous because oftenthe opening does not extend to the periphery of the iris (Figure 6).

In this presentation, I have not touched on all aspects of shallowingof the anterior chamber; for example, I have not discussed the re-lationship of trauma, inflainmationi, clhoroidal lhemorrlhage, or anumber of otlher possible factors predisposing to these conditions,such as structural abnormalities in the vitreous or causes of its forwarddisplacement in some eves. Fuirthermore, I recognize that even in the

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Shallow; Chla ber Follow(ingf Cataract Extliction2

surgical technique there are factors, other than iridectomny, suchli asexacting wound closures which are important. In this paper, myprimary concern has been witlh the relationship of the oplening inthe iris and placement of the incision in connection with obstructionby the intact vitreous face. Attention to this and other factors dis-cussed in this paper has reduced significantly the incidence of lateshallowing of the anterior chamber following seemingly uncomplicatedcataract extraction, on my services. For example, in 1957, W7eisel and12 reported an incidence of 7 per cent (14 out of 200 cases). In acomparable series, observed in 1961 and 1962. I found an incidenceof 2 per cent (4 out of 200 cases).

SUN1MARY

A review of cases at the University of Oregon Mledical School re-vealed that failure of reformation of the anterior chamber aftercataract extraction was virtually eliminated by the use of a limbus-based flap and a limbal incision carefully closed with buried sutures.However, late shallowing of the anterior chamber occurring with-out demonstrable wound leak and associated with choroidal detach-ment and hypotony still occurred in a few cases. Five years of addi-tional experience confirmed the observations reported by Weisel andme in 1957, namely, that obstruction of the pupil and iris coloboma bya forward displacement of the vitreous face was an important con-tributing factor in such cases. Rupture of the adherence of thevitreous to the iris by intensive mydriatic therapy sometimes alter-nated with miotics has been the most effective medical therapy.Point pressure on the iris through an anesthetized cornea with alubricated glass rod may disrupt some of the pupillary adhesionsand was found to be a valuable supplement to medical therapy.When non-surgical treatment was unsuccessful, peripheral iridectomyor iridotomy was performed with success in eight neglected caseswithout resorting to rupture of the vitreous face, sclerotomy, or airinjections. Attention to the vitreous obstruction in the early stagesafter cataract extraction reduced the incidence of later vitreous blockglaucoma to only six cases out of more than 3,000 cataract extractions.

Postoperative gonioscopy revealed the incidence of shallow chamberdue to vitreous obstruction of both the coloboma and pupil to beapproximately the same in cataract extractions performed with peri-pheral, as compared to complete, iridectomy provided that an ade-quate opening was made near the base of the iris. The incidence ofshallow chamber was 5 per cent when the opening did not extend

229

230 'CtIKenethl C. Stw(ian

to witlini approximately one millimecter of the base(, bltt wvas lessthan 2 pcr cent when the opening wvas basal. Forward displacementof the vitreous face with herniation throtugh the pupil was common,but vitreous herniation into truly basal iris openings seldom wasfouind. It was relatively frequent when the openings extended onlyimidway to the root of the iris. Clinical and microscopic studies re-vealed an anatomic explanation for these observations. In aphakiceves, the face of the vitreous usually was blocked from contact withthe extreme periphery of the iris by the ciliary processes and ciliarybody. It frequently was in contact with iris in the pupillary area.For cataract extraction an incision entering the anterior chamber

in the region of Schwalbe's line is recommended. The iris and vitreousare more apt to become adherent to incisions entering the anteriorchamber farther forward in the cornea and it is more difficult to(,btain a basal coloboma. For a complete iridectomy, it is recom-mended that the iris be grasped behind the sphincter so that theperipheral part can be stretched into the wound and excised. Forperipheral iridectomy, delivery of the peripheral iris into the incisionwvitlh forceps is recommended as preferable to snipping a hole in theiris with scissors introduced into the anterior chamber. Such openingswvere found to be small and seldom basal. Attention to these and otherfactors, in our cases, has significantly reduced, although not eliminated,late shallowing of the anterior chamber without demonstrable woundleak.

REFERENCES

1. Christensen, Leonard, Epithelization of the anterior chamlber, Tr. Am. Ophth.Soc., 58:284-96, 1960.

2. Weisel, John, and K. C. Swan, Mydriatic treatment of shallow chamber aftercataract extraction, Arch. Ophth., 58:126-9, Jtuly, 1957.

3. Chandler, P. A., and A. E. \Iaumenee, A mnajor cause of hypotony, Tr. Am.Acad. Ophth., 65:563-74, Jtuly-Aug., 1961.

4. Chandler, Paul, Glaucoma from pupillarv block in aplhakia, Tr. Am. Ophth.Soc., 59:96-102, 1961.

D. Swan, K. C., Basal iridectomny for prevention and treatment of persistentshallow chamber after cataract extractioin, Eye Digest, WVatson GaileyFotundation, Jan., 1958.

6. Swan, K. C., and R. C. Cowger, Mlydriatic treatment of slhallow chamber aftercataract extraction, Correspondence, Arcl. Ophth., 59:151-2, Jan., 1958.

7. Shaffer, R. N., The role of vitreous detachment in aphakia aind malignantglaucoma, Tr. Am. Acad. Ophth., 58:217, 1954.

8. Irvine, S. R., Vitreous Changes Before and After Cataract Extraction. InDiseases and Suirgery of the Lens. St. Lotiis, C. V. Mosby, Co., 1957,pp. 166-85.

9. Swani, K. C., Surgical Anatomiiy, in Symposiumiii oIn Glatuicomai-It. St. Loutis,C. V. Mlosby, Co., 1959, pp. 46-9.


DISCUSSION

DR. S. RODMAN IRVINE. The problem of delayed flat chambers, hypotony,and detached choroid, is to the ophthalmologist what slicing, hooking, anddubbing is to the golfer-a topic for ready discussion but one which isnever resolved.

Practically everyone in this audience has written on the subject ordiscussed it at one time or another. Dr. Swan has made three new observa-tions. (1) The "vitreous" block, as he calls it, may be corrected by mechani-cal rupture of the adhesions of the iris to the vitreous face by applicationof pressure to the iris through the cornea with the tip of a glass rod. And(2) the demonstration that a posterior chamber is usually present in aphakiaand (3) that the adhesions form first around the pupillary margin.

I think that most experienced surgeons agree with Dr. Swan that peri-pheral iridectomy, as he describes it, is advisable and is one factor inreducing incidence of the syndrome. Of course, as he cautions, one must notcut too peripherally and tear the iris so as to damage the major arterialcircle of the iris. Dr. Swan stresses the importance of good wound closurein his newer technique of half lap type incision, but, even with this, hisincidence of delayed flat chamber was 7 per cent until he paid moreattention to the iridectomy, reducing it to 2 per cent by making the iridec-tomy more peripheral.

Dr. Swan prefers peripheral iridectomy to posterior sclerotomy in theinitial treatment of cases even though the eye is soft and no evidence ofglaucoma has been established.

Last year we heard Dr. Chandler discuss a later result of this syndrome,namely, normal or increased pressure, for which he advocated peripheraliridectomy. For the record, I would like to review the mechanism involved,as it appears to me.

Aqueous has to go around or through the vitreous to get into theanterior chamber. I believe that, normally, aqueous can permeate thenormal vitreous hyaloid [slide] but, certainly, if there is slight wound leak,or inflammation of any kind, the hyaloid can become altered and becomeadherent to the iris. The vitreous then comes forward, either because ofdetachment of the vitreous posteriorly, or because of pooling of the aqueousbehind the vitreous, pushing it forward, or because of flattening of thechamber due to wound leak-or perhaps all of these.

As a result of the vitreous coming forward, it coincidently contracts andpulls on the vitreous base, tending to open the supraciliary and supra-choroidal space, allowing transudation to occur here. This further increasesthe pressure in the posterior vitreous space relative to the anterior chamber,exaggerating the shallowing of the chamber.

If the condition occurs suddenly, and the eye is very soft, one immediatelysuspects wound leak. As Dunnington and others have shown, these leaksare not always easy to demonstrate. Last year Shaffer suggested demonstra-

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tion of leak by injecting weak fluorescein into the anterior chamber and Isuggested study of the wound with the corneal microscope after peritomy.

If no leak is found and the eye is still hypotensive one would have toassume decrease in aqueous formation due to separated choiroid. If thecondition develops slowly, that is, with gradual flattening over a numberof days, one might assume that there is a pupillary "vitreous" block withsuppression of aqueous secretion, as is emphasized by Maumenee andChandler.

Now, as long as a posterior chamber is present, and Swan has demon-strated this with his pictures, iridectomy will equalize the pressure andtend to deepen the anterior chamber. I have proven this a number of timesin shallow chamber following cyclodialysis and hypotony, by deepening thechamber simply by iridectomy. To attempt to prove this theory of relativepupillary block in a soft eye in phthisis bulbi with shallow chamber, I havedeepened the chamber by simple iridectomy prior to enucleation. I believethis concept of relative pupillary block should be emphasized in our appraisalof these cases.

If the entire back of the iris becomes adherent to a hyalinized vitreous,as sometimes occurs after loss of vitreous, simple iridectomy will not deepenthe anterior chamber and one has to make an opening into the vitreous andtrephining over the separated choroid, and, in some instances causing avitreous fistula posteriorly, to reverse the flow of fluid so that the pressurebecomes relatively lower in the vitreous and posterior chamber with respectto the anterior chamber. I discussed this in a lecture on the vitreous in 1955,at the Proctor meeting, and Shaffer has also discussed this concept, as haveothers.

So, to summarize the treatment-one tries medical means, moving thepupil with miotics and mydriatics, as originally recommended by Reese, andnow, by the new technique of Swan-massaging the iris with a glass rod-closing the wound leak if any is demonstrable-then peripheral iridectomy-then posterior sclerotomy-then section through the vitreous and creationof a vitreous fistula posteriorly, through a posterior sclerotory wound overthe detached choroid.

I want to present a final slide showing how the incidence of thiscomplication can vary from year to year in the hands of a single surgeon[slide]. In all these cases, I made a keratome incision at the posterior limbus,after peritomy, and enlarged the wound with McGuire scissors. I used threeto five post-placed 7-0 corneoscleral sutures on Greishaber needles.We see an incidence of delayed flat chambers comparable to what Dr.

Swan reports. Prior to this series, in about 1300 cases, when I was usingpure corneal sections with a knife, I so rarely encountered this syndromethat I considered it less important than the 2 per cent incidence of vitreoussyndrome. I do believe that faulty wound healing is the primary problem,leading to the cycle of events of forward displacement of vitreous, tractionon the supraciliary and suprachoroidal space, choroidal detachment, and

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increased pressure in the vitreous chamber relative to that in the anteriorchamber.

For the past year, I have again used knife sections, more forwardlyplaced in approximately 100 cases and have rarely encountered thesyndrome.

Dr. Swan's presentation is most important and thoroughly appreciated byall of us experienced enough to have encountered delayed shallowing ofthe chamber, detached choroid, and hypotony. As he so aptly puts it-manycauses may be contributory-and he has emphasized only the role ofperipheral iridectomy.

DR. WALTER S. ATKINSON. It is always stimulating to hear Dr. Swan'sthoughtful presentations.

Like other complications in cataract surgery, shallow or flat anteriorchambers, particularly at the first dressing, are rare and usually are causedby a leaky wound which responds to repair if the condition persists.

For those that occur later, after the tenth day, the cause often is noteasily demonstrated. At that time the pupil is usually dilated which mayclose the peripheral iridotomy or iridectomy openings made at the time ofthe round pupil extraction.

It would seem logical to contract the pupil to open the peripheral holeor holes already present in the iris and allow the aqueous to come forwardfrom the posterior to the anterior chamber as obtained by making a peri-pheral iridectomy as advocated by Dr. Swan. To dilate the pupil more whenthe chamber is flat one would expect the iris to become adherent to thewound forming anterior synechia.

DR. KARL W. ASCHER. One question to the essayist and to the audience: Isthe frequency of flat chambers after cataract operation greater when youuse hyaluronidase?

DR. HAROLD GIFFORD. Just one note on the technique of doing a completeiridectomy. Dr. Swan pointed out that it is important to get the root of theiris. A few years ago I showed a method of grasping the iris in the centerbetween the sphincter and the base. When this is pulled out it pulls thebase with the iris, and then you reverse the scissors.The usual iridectomy is done with the curve of the scissors against the

eye. Reverse the scissors and cut the other way, the iridectomy comes outwith straight pillars. By picking the iris up in the center you get a nice, fulliridectomy with a clean bottom. It does away with the root that is leftbehinld. It leaves vou with beautifuil pillars.

It is a most dramatic thliing to see the chambers deepen in your office.Put in a drop of 10 per cent nieosvnephrine and it will deepen while youwatch it. The next day the chamber may be flat again. Put in another dropand it will deepen while you watch it.

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Kenneth C. Swan

As soon as the neosynephrine wears off the chamber flattens again. Aboutthe fourth day it remains deep and everybody is happy.

I would like to ask Dr. Swan if he has any explanation of this effect.

DR. HARVrEY E. THORPE. I want to thank Dr. Swan for calling this importantsubject to our attention.One of the things he has shown in this study is that by means of

biomicroscopy and postoperative gonioscopy he was able to better arriveat the basic pathology of complications in these cases with shallow anteriorchamber. His gonioscopic illustrations of postoperative findings demon-strated that the iridectomy one does and considers to be basal is frequentlyproven not to be basal and that the buttonhole iridectomy which one maythink to be peripheral turns out not to be truly peripheral unless specialpains are taken to make it so. At the risk of repetition, I wish to stress thatperipheral iridectomy must be penetrating through all the iris layers andmust remain patent to be effectual.

Postcataract extraction iridovitreous adhesions may cause complete seclu-sion of the pupil as well as adhesion of the margins of the surgical coloboma.This leads to iris bombe and ultimate angle block. The essayist hasdemonstrated this sequence of events. He confirmed that the iridovitrealextensive adhesions are responsible for some of the pupil block phenomenawhich Chandler and others have described. Biomicroscopy can readily bedone six or seven days after cataract extraction. Gonioscopy with our fourmirror gonioprism can usually be performed without danger five to sixweeks after surgery. These methods of examination afford an accurateappraisal of the complicating factors and point to the necessity of restoringcommunication between the anterior and posterior chamber by early forcedmydriasis, by breaking posterior synechia in the manner shown by Dr. Swanand if necessary by surgical intervention.

DR. SWAN. I wish to thank Dr. Irvine for his fine discussion, and particularlyfor bringing out the mechanism. Also I want to pay tribute to his studies ofthe vitreous after cataract extraction. He has conducted such studies formany years. He mentioned "wound leak." Dr. Cowger and I, some yearsago, studied the relationship of unintentional filtration after cataract extrac-tion to shallow chamber. We found no correlation between the incidenceof shallow chamber and even large filtrations under the conjunctiva. Weconcluded that a limbal leak was not a factor as long as the fluid wasretained under the flap and did not leak out through the conjunctivalincision into the fornix.

Dr. Atkinsoni has brought up all importanit poinit. If the incision entersthe anterior chamber well forward, it is coniceivable that wide dilatationl ofthe pupil might block anl iridectomy in the extreme periphery. This is oniereason why I like to have the incision enter in the region of Schwalbe's line.

I wish I could answer Dr. Ascher's question about hyaluronidase. I assume

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Shallow Chamiiber Following Cataract Extractiotn 235

he means by retrobulbar injectioni. There is little doubt that it does enlhanicethe spread of the local anesthesia, and that it may prolong anid iintensifyhypotony when combined with epinephrine.

Dr. Gifford has mentioned the shape of the iridectomy in relationi to thecurve of the scissors. It is something that I will investigate.

Recurrence of shallow chambers has bothered uIs. We also have hadrecurrence oIn the day following restoration with mvdriatics. At first Ithought it might be related to the known depressant effect of epinephrine onthe rate of formation of the aqueous. But in most of these cases, thisfunction already is depressed. We have founld the solution to be moreintense mydriasis, continued oIn a 24-hour schedule.

I appreciate Dr. Thorpe's discussioni and particularly his emphasis oni theuse of the gonioscope. The time of application of the gonioscope is importantafter cataract extractioni. Too early an applicationi mav cause serious trouble.Eight days, by the way, is the earliest we have applied the glass rod.

RELATIONSHIP OF BASAL IRIDECTOMY TO SHALLOW ...

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