Pediatrics Update: Amblyopia Therapy Is for Older Children Too

Amblyopia (lazyeye) is characterizedbyunilateral orbilateral impairmentin visual acuity,uncorrected by opticalmeans, without detectableanatomic damage in theeye or visual pathway.¹ Adiagnosis of amblyopiamust satisfy 3 criteria²:

• The best corrected visualacuity is impaired in 1or both eyes.
• There is a history of 1 ormore amblyopia-inducingconditions that affected theamblyopic eye during theperiod of visual immaturity.
• There is no organic abnormalityof the visual systemthat could fully accountfor the impaired visualacuity.

Amblyopia may beclassified according to theconditions by which it istypically induced. Theforms of amblyopia includethe following^1-3:

Strabismic. Amblyopiadevelops in about40% of children with strabismus,the most commoncause of amblyopia. Esodeviations(turning in ofthe eye) are more commonlyassociated with amblyopiathan are exodeviations(vertical deviations).

Refractive. In patientswith isometropic amblyopia,uncorrected bilateralhigh ametropia causesbilateral blur. In patientswith anisometropic amblyopia,image distortion andunequal visual inputscause unilateral blur.

Form deprivation. This condition is associatedwith media opacity,eyelid ptosis, and eyelidhemangioma that obstructthe visual axis.

Iatrogenic. This formis induced by occlusion(patching).

MANAGEMENT

Successful treatmentof amblyopia must incorporate2 key strategies.²The first is to optimize theclarity of the retinal image in the amblyopic eye. Thisis accomplished by providinga clear visual axis (eliminationof any obstacle to vision)and correcting significantrefractive error. Thesecond is to intensify theneural stimuli to the visualcortex. This is achieved bylimiting the stimulus to thenonamblyopic eye, thereby"forcing" the amblyopic eyeto function.

Treatment optionsinclude the following^2-4:

• Occlusion, either parttimeor full-time.
• Optical degradation withopaque contact lens orgraded transparent filterson an eyeglass lens.
• Defocusing (penalization)through the applicationof atropine 1%, a cycloplegicagent, to thestronger eye.
• Active therapy consistsof occluding the strongereye while exposing theamblyopic eye to visualstimuli.

AN IMPORTANTNEW STUDY

Traditionally, treatmentof amblyopia in childrenolder than 9 yearswas not recommended becauseexperts believedthat the visual system wasmature by that age. However,a new study from the Pediatric Eye Diseases InvestigatorGroup showedthat age should not be alimiting factor in initiatingamblyopia therapy.⁵ Thestudy enrolled 507 children,aged 7 to 17 years,with amblyopia. All participantswere provided withmaximal optical correction,and one group wasrandomly selected to receiveadditional treatment(2 to 6 hours per day ofprescribed patching combinedwith near visual activitiesfor all patients, plusatropine sulfate eyedropsfor children aged 7 to 12years). Children whoshowed improvement inthe amblyopic eye of 2 ormore lines of vision on astandard eye chart wereconsidered responders.

The researchersfound that 53% of childrenaged 7 to 12 years in thetreatment group were responders,compared withonly 25% of children ofthe same age in the opticalcorrectiongroup. In the13- to 17-year-olds, 25% ofthe treatment group and23% of the optical-correctiongroup were responders.In this age group,47% of children in thetreatment group who hadnever been treated for amblyopiawere responders, compared with only 20% ofthose in the optical-correctiongroup.

Because it was unclearwhether improvement invisual acuity could besustained once treatmentwas discontinued, the researchersstopped short ofrecommending a changein current clinical practice.However, they are conductinga 1-year follow-upstudy to determine the degreeof amblyopia that recursamong responders.

SOCIAL STIGMAOF GLASSES

Wearing glasses mayaffect children socially. In arecent 1-year study, theauthors examined datafrom 6536 preadolescentchildren who wore glasses,had manifest strabismus, orhad a history of wearingan eye patch.⁶ Psychologistsinterviewed the childrento identify the amountof bullying they were involvedin, either as victimsor as perpetrators. Resultsshowed that after adjustmentfor sex, visual impairment,social class, and maternaleducation, these childrenwere 35% to 37% morelikely than other childrento be targets of physical orverbal bullying. Considerrecommending contact lenses instead of glassesfor children who feel especiallyvulnerable.

References:

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Keech RV. Practical managementof amblyopia.

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Press LJ, Kohl P. Vision therapy foramblyopia. In: Moore BD, ed.

EyeCare for Infants and Young Children

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Scheiman MM, Hertle RW, BeckRW, et al. Randomized trial of treatmentof amblyopia in children aged7 to 17 years.

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Horwood J, Waylen A, Herrick D,et al. Common visual defects and peervictimization in children.

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