Cycloplegic Retinoscopy in Infancy

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Retinoscopy in infancy: cycloplegic versus non-cycloplegicC-18551 O/D

Fabrizio Bonci, Dip. Optom (ITA), MCOptomLuigi Lupelli, Dip. Optom (ITA), FAILAC, FIACLE, FBCLAThe assessment of refractive status in very young children is often not conducted in the same manner as for adult patients. In particular, the child’s age, their co-operation and dynamic refractive status will be key factors which influence the accuracy of refraction. For this reason, it is often necessary to choose procedures which inhibit or minimise accommodative activity. This can be achieved by fogging with positive lenses or rousing the tonic (resting) accommodation (dry refraction), or with pharmacological agents (wet refraction). This review article compares the two approaches, focusing on the retinoscopy techniques.

Dry retinoscopyStatic retinoscopy The patient views a distance target (four-

six metres) so that accommodation is

presumed to be static and in a relaxed

condition. The fixating eye (contralateral

to the one being examined) should be

adequately “fogged” with a positive lens

(resulting in an “against” movement seen

on the retinoscopy swipe).1 For children,

maintaining fixation at this distance

can be difficult and new computerised

test charts generally provide dynamic

and more interesting targets to view

than a standard spotlight (Figure 1)

to help with this. It is also possible

to download a number of videoclips,

especially cartoons, with different

animations. Practitioners should also

consider not using a phoropter or trial

frame when conducting retinoscopy

on a very young child, as this can be

intimidating for the child. It is preferable

to use single trial lenses or a lens rack.

Speed during retinoscopy is essential

when performing this technique in

young children, especially as they

maintain fixation only for very short

periods of time. In cases of fluctuation of

accommodation, the practitioner should

follow the “with” movement, ignoring the

occasional “against” movements seen.

Yeotikar et al.2 evaluated the difference

in refractive error in non-strabismic

children between the ages of seven years

and 16 years, using static retinoscopy

under two conditions – first by fogging

the contralateral eye with a positive

lens and second with cycloplegia using

cyclopentolate 1%. The study found

that the average difference in refractive

error between these two conditions

was only 0.29DS more hypermetropic

with cyclopentolate, highlighting the

accurate results that can be obtained

when there is adequate accommodative

control during static retinoscopy.

Furthermore, Chan and Edward3

suggested a calculation which can be

used to match the dry retinoscopy

result to that which would be obtained

using cyclopentolate 1%, in children

between 3.5 to five years of age. The

astigmatic component is kept the same

whilst the spherical component found

in both meridians is multiplied by 1.45

and a value of 0.39D is added. However,

this depends on an accurate static

retinoscopy result having been obtained.

Mohindra retinoscopy The Mohindra technique, also known

as near retinoscopy or near monocular

retinoscopy, carries the main advantage

of being child-friendly and requiring less

co-operation from the child.4 In this case,

the stimulus is the dimmed light source

of the retinoscope in a darkened room.

The darkness of the room will facilitate

the child to keep their attention on the

retinoscope’s light. The retinoscope

is held at a distance of 50cm (errors in

distance are not clinically relevant),

with hand-held trial lenses used to find

the neutral point. The accommodation

activity during the examination is small

and the same in both eyes. It is important

during the examination to keep the light

of the retinoscope on the child’s pupil

Figure 1 Examples of exciting targets presented by computerized test charts during retinoscopy. Different face expressions allow to the practitioner to talk to the child to maintain attention on the target (Courtesy of Thomson Software Solutions, UK).

Approved for: Optometrists Dispensing Opticians 4 4

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(to see the retinal reflex) for only a short

period of time so as not to stimulate

accommodation; subsequently the

optometrist’s attention should be focused

on the pupil, watching for maximum

dilation (indicating no accommodation).5

The procedure should be carried out

with one eye occluded, preferably by the

parent, while the other eye is evaluated.

However, Wesson et al.6 confirmed that

there is no substantial difference in the

result if binocular fixation is allowed

(Figure 2); indeed this can be useful if the

infant is resistant and becomes agitated

with occlusion. Several people advocate

neutralisation of the two principal

meridians of the eye separately, using

loose spherical trial lenses. However,

Saunders and Westall7 confirmed that

the accuracy of the technique can

be improved using a combination of

spherical and cylindrical lenses instead.

Once the retinoscopy result is obtained, the

refractive error was originally calculated

by adding -1.25DS to the gross finding.8,9

Saunders and Westall7 have reported

that the accuracy can be improved if

-0.75DS is added instead, for children

aged between 0-2 years, and -1.00DS

added for those children over two years

of age. They also affirmed that the result

achieved by the Mohindra procedure in

children between six months and four

years of age is similar to wet retinoscopy

(using cyclopentolate 1% – see later),

with a difference of only 0.50DS. Others

have reported similar results,10 and

certainly no differences greater than

1.00DS,11 whilst similar results were

also obtained for children with Down’s

syndrome12 and even in adults.13

The Mohindra technique is useful for

practitioners in Europe who are not

permitted to used cycloplegic agents,14

whilst there are benefits for conducting

frequent follow-up assessments without

repeated use of cycloplegic agents.15

One must remember, however, that the

accuracy of results will naturally depend

on the practitioner’s experience.16

Cycloplegic agentsControl of accommodation in children

of pre-school age is more commonly

achieved by pharmacological means,

using cycloplegic agents such as

cyclopentolate and tropicamide; atropine

can only be used by therapeutically

qualified practitioners. All of these drugs

are muscarinic receptor blockers, thus

they work by blocking the muscarinic

receptors in the ciliary body, which

in turn prevents accommodation.

A mydriatic effect is concurrently

achieved by inhibiting muscarinic

stimulation of the iris sphincter muscle.

An ideal cycloplegic would have no

ocular and systemic adverse effects.

Also, it should produce a rapid onset of

cycloplegia, blocking accommodation

completely for an adequate period

of time, before swiftly restoring

accommodative ability.17 Several

studies have reported both ocular

and systemic side effects (especially

using atropine) in those children who

have had a cycloplegic refraction,

in addition to expected mydriasis

and cycloplegia, as detailed later.18

Drug selection and instillationCycloplegia is an invasive technique

which can be uncomfortable, or even

distressing, for the child. This is notably

so because the acidic pH of the cycloplegic

agent leads to stinging on instillation.

Some practitioners advocate the use of a

local anaesthetic prior to instillation of

the cycloplegic agent; proxymetacaine

0.5% is the drug of choice as it stings less

than other topical anaesthetics. However,

this is not always recommended due to

the risks associated with an anaesthetised

cornea. To facilitate the application

of cycloplegics, cyclopentolate has

been instilled in spray form onto the

eyelashes and the closed upper lid.19

Practitioners should also be conscious

of their instillation technique, since

different degrees of cycloplegia between

the eyes can occur, especially if the

child does not keep their eyes open wide

enough and/or if there is significant post-

instillation tearing (which is very likely).

As such, practitioners can opt to instil

the higher concentration of cycloplegic

agent and/or instil further drops if

regular review (eg, periodic measurement

of the amplitude of accommodation)

reveals differing levels of cycloplegia.

Differences in the main cycloplegic

agents are summarised in Table 1. The

optometrist should select an appropriate

agent considering factors such as the

patient’s age and whether they have

dark, or light coloured, irides. Adequate

cycloplegic effect could be achieved

with tropicamide in a teenage patient

suspected of having latent hypermetropia,

for example, whereas cyclopentolate

is likely to be required for an infant

suspected of having an accommodative

esotropia. Those with light coloured

irides may exhibit an increased response

to drugs as compared with darkly

pigmented irides, and therefore a lower

concentration/dose ought to be selected.

Overdose of cycloplegic agent has to

be avoided in children with Down’s

syndrome or those affected by cerebral

Figure 2 Mohindra retinoscopy. Hand-held trial lenses are placed in front of both eyes whilst the child fixates the retinoscope light. The procedure should be run in darkened room (the high level of room light in this image was for photographic purposes only).

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palsy, trisomy 13 and 18, and other

central nervous system (CNS) disorders.

This is because toxicity increases in

these people, especially children, which

causes stimulation of the medulla

and the cerebral centres, leading to

hallucinogenic effects similar to those

caused by LSD drugs.20,21 These reactions

generally occur within 20-30 minutes

after administration.22 Tropicamide

1% should be considered in these

children as opposed to cyclopentolate.

Cyclopentolate Cyclopentolate 0.5% or 1.0% is

commonly used by practitioners as

the cycloplegic agent of choice for

paediatric examinations. The cycloplegia

achieved is not too deep, as compared

with atropine, but it is quicker in

onset, often achieved after 30 minutes

from its administration. Recovery of

accommodation is typically between six-

12 hours after instillation whilst mydriasis

resolves by 24 hours after instillation.

Although full cycloplegia is achieved

with atropine, the cycloplegic refractive

results obtained with cyclopentolate

are comparable in “normals”,23 high

hypermetropic children24,25 and also

those children with strabismus.26,27

For children under the age of three

months, it is advised that two drops of

cyclopentolate 0.5% are used as opposed

to 1%.28 This is becasue drug absorption

through the conjunctival epithelium and

skin is more rapid in infants compared

to adults,29,30 due to immature metabolic

enzyme systems in neonates and young

children, which may prolong the effects

of the drug.31,32 The main side effects

of cyclopentolate include incoherent

speech, hallucinations and disorientation,

psychosis and visual disturbances.33,34

Tropicamide This is an anti-muscarinic drug with

short-lasting effect on the pupil

(mydriasis) and on accommodation

(cycloplegia) at the 1% concentration.

Although tropicamide is mostly used for

mydriasis, to examine the optical media

and the ocular fundus, several studies

have suggested that this drug can be used

for a cycloplegic effect.35 In particular,

it is a cycloplegic agent that can at least

detect latent hypermetropia, for example

in school children, teenagers and those

in their early 20s, with otherwise normal

refractive status and/or with moderate

hypermetropia,36 as well as for children

during the post-natal period.37 In adult

patients undergoing refractive surgery, a

study showed no significant difference

in cycloplegic refraction between

tropicamide 1% and cyclopentolate

1%.38 In the same patients, however,

the study showed that cyclopentolate

was more effective than tropicamide

in reducing accommodative amplitude

in adult myopes (near-point testing).

Atropine sulphateThis is a natural alkaloid extracted

from the deadly nightshade (Atropa

belladonna) plant. Its administration

is justified in children of pre-verbal

age or when other cycloplegic agents

fail to produce a satisfactory level of

cycloplegia. Atropine is administrated

three times a day during the three days

before the eye examination. Associated

mydriasis decreases in two weeks after

the refractive examination. This drug is an

antagonist of the muscarinic acetylcholine

receptors, thus it dampens mediation of

the parasympathetic nervous system. As

a result, systemic absorption of atropine

can lead to difficulties with swallowing

food (opposed effects of the vagus nerve),

inhibition of the salivary glands leading

to a dry mouth, and reduction of sweating.

Atropine can also increase firing of the

sino-atrial node (SA) and conduction

through the atrio-ventricular node (AV)

of the heart, leading to tachycardia. It

also decreases bronchial secretions,

which can make breathing difficult.

Other side effects that have been reported

include dizziness, nausea and sensation

of being unbalanced and allergic

reactions of the eyelids and conjunctiva.

Atropine is able to pass through the

blood-cerebral-barrier and alter the state

of consciousness of the child. Therefore,

in order to minimise the systemic

absorption of atropine, the practitioner

can gently press the punctum of both eyes

and keep the patient’s head tilted back.

A recent study39 compared the

cycloplegic efficacy of homatropine

2% and atropine 1% in children

between the ages of four and 10 years by

retinoscopy and automated refraction.

As expected, the study reported that

homatropine produced a significantly

lesser cycloplegic effect than atropine,

Mydriasis Cycloplegia

Agent Concentration Max effect Recovery time

Max effect

Recovery time

Atropine 0.5-3.0% 1-2 hours 7-12 days 60-180 min 6-12 days

Cyclopentolate 0.5-2.0% 30-60 min. 1 days 25-75 min 6-12 hours

Tropicamide 0.5-1.0% 20-40 min 6 hours 20-35 min 4-6 hours

Homatropine 2.0-5.0% 40-60 min. 1-3 days 30-60 min 1-3 days

Scopolamine 0.25% 20-30 min 3-7 days 30-60 min 3-7 days

Table 1 Cycloplegic and mydriatic effects amongst the main cycloplegic drugs used in optometric practice

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with residual accommodation being

greater (1.80±0.40D with atropine

vs. 3.10±0.50D with homatropine;

p<0.001). Another study40 compared the

cycloplegic effect obtained at 90 minutes

after administration of two drops of

atropine 0.5% to that obtained after

three times daily instillation of atropine

0.5% for three days, in strabismic

children. It was found that although

residual accommodation was greater

at 90 minutes after instillation (1.00D)

compared with three-day atropinization

(0.50D), the former still allows a more

rapid and less toxic assessment of

refraction than the usual three-day dose.

Indications for cycloplegic refractionThere are several instances

when a cycloplegic refraction

is indicated, including:

• Hypermetropia over +5.00D

• Anisometropia more than 1.50D

• Suspect and/or manifest strabismus

(especially esotropia)

• Family history of strabismus, high

hypermetropia and amblyopia

• In the presence of unstable esophoria,

pseudomyopia and asthenopia

• Poor cooperation/fixation of the child

• When the retinal reflex during

retinoscopy changes motion

or brightness due to dynamic

accommodative status.

There are also some instances

where cycloplegic refraction

is contraindicated, including:

• Cases where administration of

cycloplegic agents will cause undue

stress for the child, resulting in a

complete lack of co-operation

• Risk of ocular and/or systemic side

effects (which are more likely with

atropine than cyclopentolate and

tropicamide)

• Risk of developing acute angle closure

glaucoma in those with a shallow

anterior chamber (especially with

cyclopentolate)

Conducting wet retinoscopy Cycloplegic retinoscopy is carried out in

a similar way to dry static retinoscopy.

Despite pharmacological control of

accommodation, some co-operation

of the child is still required to keep

fixation during the examination, so that

off-axis aberrations do not distort the

retinoscopic reflex. Zadnick et al.41 found

that the repeatability of retinoscopy

under cycloplegia is poorer than non-

cycloplegic conditions, mainly due to

the irregularity of the retinoscopic reflex

through a dilated pupil. For this reason

it is important for the practitioner to

concentrate only on the central portion

of the pupil, ignoring the movement

seen in the peripheral annulus.

Objective automated refractionWhen a cycloplegic retinoscopy result

has been obtained, it can be useful to

conduct objective automated refraction

too, for comparison of the results. A

study42 comparing cycloplegic refraction

measurements using the hand-held

autorefractor (Retinomax), a table-

mounted autorefractor (Canon FK-1)

and streak retinoscopy in a large cohort

of children between 24 and 72 months

of age found no significant difference

in the mean spherical equivalent (MSE)

refractive error between the table-

mounted autorefractor (1.03±1.64D)

and streak retinoscopy (1.09±1.58D,

p=0.66). However, the MSE using the

hand-held Retinomax (0.80±1.43D)

was significantly different (p=0.0004)

to streak retinoscopy. Astigmatism

measured using the hand-held

(-0.89±0.51D) and table-mounted

(-0.83±0.61D) autorefractors were

significantly greater than that obtained

with retinoscopy (-0.58±0.56D,

p=0.0003). Therefore, practitioners

should remember that autorefractometry

and videorefractometry, although

useful as a guide and screening tool,

are not accurate enough to base actual

prescribing decisions upon in pre-

school children.42,43 Issues of ensuring

correct fixation on the target tend to be

the primary reason for the discrepancy,

but even in co-operative older subjects,

variable readings can be obtained

from different autorefractor tools.44-45

Dry autorefraction seems particularly

inaccurate in hypermetropia46 and

astigmatism in children of pre-verbal

age,47 although hand-held autorefraction

devices can evaluate astigmatism

without administration of cycloplegic

drugs, with the same repeatability as

wet retinoscopy.48 Wet autorefraction

generally seems more accurate if

it is compared to the subjective

refraction under cycloplegia.49

Practitioners should also remember that

cycloplegic drugs might temporarily

modify the structures of anterior

chamber, inducing astigmatism or

modifying an existing astigmatic

ametropia. This could occur because

there is a change in intraocular pressure

(IOP) under cycloplegia, which alters

the position of the crystalline lens

from the normal corneal distance.

These modifications have an effect on

the refraction, but this is difficult to

quantify in terms of refractive power.50

Conclusion During the refractive assessment it is

necessary to control and often inhibit

accommodative function, especially in

paediatric cases. This can be obtained

using dry and wet techniques, both of

which are appropriate for identifying

the most appropriate correction.

Although the refractive assessment

should be carried out as naturally

as possible, when the practitioner

encounters uncooperative children or

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1. Which of the following statements is TRUE?a) Atropine produces cycloplegia within 2-3 hours and recovery of accommodation in 2 daysb) Cyclopentolate produces cycloplegia within 30 minutes and recovery of accommodation in 12 hoursc) Homatropine produces cycloplegia in 20-30 minutes and recovery of accommodation in 24 hoursd) All of the above

2. Which pharmacological agent should be considered in a child with Down’s Syndrome?a) Atropine b) Homatropinec) Cyclpentolate d) Tropicamide

3. When should Mohindra’s retinoscopy technique be performed? a) In all children b) Only in children aged 7-10 yearsc) Only in young children with moderate astigmatism d) In pre-verbal children

4. How should Mohindra’s retinoscopy technique be performed?a) In darkness, fixation being on the retinoscope light, using hand held lensesb) In room lighting, fixation being on a high contrast target at the retinoscope mirror c) In darkness, fixation being on a spotlight at 6 metres, using hand held lensesd) In room light, fixation being on a high contrast target at 6 metres, under cycloplegia

5. Which of the following statements regarding cycloplegic refraction is TRUE?a) It should be considered in children with high hypermetropia or strabismusb) It should be considered in every child at every sight testc) Atropine is the cycloplegic of choice for a 5-year-old childd) Objective automated refraction should be used for prescribing decisions

6. Which of the following is NOT a side effect of cyclopentolate?a) Incoherent speechb) Hallucinationsc) Mydriasisd) Conjunctival hyperaemia

PLEASE NOTE There is only one correct answer. All CET is now FREE. Enter online. Please complete online by midnight on May 4, 2012 – You will be unable to submit exams after this date. Answers to the module will be published on www.optometry.co.uk/cet/exam-archive. CET points for these exams will be uploaded to Vantage on May 14, 2012. Find out when CET points will be uploaded to Vantage at www.optometry.co.uk/cet/vantage-dates

Module questions Course code: C-18551 O/D

those with risk factors for binocular

vision anomalies the refraction should

be performed under cycloplegia.

Tropicamide seems to be as effective

as cyclopentolate for measurement of

refractive error in most non-strabismic

infants, particularly at the 1%

concentration, so it should be considered

more often in paediatric eye care in

order to reduce the possibility of adverse

reactions. Where there is suspicion of a

binocular vision anomaly, cyclopentolate

should be the agent of choice.

About the authorsFabrizio Bonci is an optometrist and

clinical research fellow at the division

of clinical neuroscience and mental

health, Imperial College, London, and

the Faculty of Medicine, Charing Cross

Hospital, London. Luigi Lupelli is an

optometrist, professor in contact lenses

at the Faculty of Science, Department

of Physics, (Optics and Optometry)

at the University of Roma Tre, Italy.

ReferencesSee www.optometry.co.uk/

clinical. Click on the article title and

then on ‘references’ to download.

Cycloplegic Retinoscopy in Infancy

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