occlusion amblyopia

Occlusion amblyopia is an iatrogenic loss of vision in the good eye, caused by excessive patching of that eye to treat amblyopia in the fellow eye.¹ The formerly amblyopic eye may become the dominant eye, and eccentric fixation may develop in the occluded eye.²

Children up to 5 years of age are at risk, and susceptibility falls with age until it is about null at 12 years. The loss is usually reversible, although irreversible cases have been reported.² To prevent occlusion amblyopia, young children alternate occlusion between the eyes, for example 3 days on the sound eye and then 1 day on the amblyopic eye during the first year of life. Parents are warned of the risk and asked not to miss follow-up visits once patching starts.²

Some texts use the term more broadly, for amblyopia in any eye occluded during the critical period, with monocular congenital cataract and monocular lid ptosis as common causes.³ In the narrower usage, those conditions count as stimulus deprivation amblyopia.¹ Patching to treat an eye disease or injury can cause the same loss, and the sooner the occlusion is removed, the better the visual outcome.³