Lazy Eye

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Amblyopia, informally called “lazy eye,” is the leading cause of decreased vision in children. It is caused by abnormal visual development, usually in one eye and rarely in both eyes, as a child. Vision in the affected eye is decreased, causing the brain to stop communicating with that eye. This causes the affected eye to wander, or drift. The eye does not track with the “good,” or stronger eye, and eventually the affected eye wanders inward (toward the nose), or sometimes outward. The brain then relies on information sent only by the unaffected eye. It can be present at birth, however amblyopia usually develops between birth and seven years of age.

Children often do not realize they are having trouble seeing, but sometimes they exhibit behavioral signs or other indications of visual problem. These signs include tilting of the head, squinting, or closing one eye. Parents may notice that the child is clumsy, which is caused by poor depth perception (two functioning eyes are required for proper depth perception). Parents may also notice that the child’s eyes do not move, or track, together. Infants with amblyopia may cry when one eye is covered because they cannot see well out of the affected eye. Causes of amblyopia include strabismus, a muscle weakness in one eye that causes the eyes to fail to move together, and refractive errors like astigmatism, which causes one eye to be shaped differently than the other thereby causing blurred vision in the affected eye. Rarely, a cataract may cause decreased vision in a child’s eye. Risk factors for amblyopia include premature birth, low birth weight, a family history of it, and certain developmental disabilities.

It is imperative that amblyopia be found and treated early, otherwise the visual impairment may become permanent. Pediatricians routinely perform visual screenings at each well-child visit from birth to 18 years of age. If the pediatrician, family members, or teachers have any concerns about a child’s vision, referral to a pediatric ophthalmologist is imperative. This needs to be done as early as possible because the older the child is, the harder it is to correct amblyopia. If the amblyopia is caused by a condition, such as the ones described above, that condition must be treated and corrected first.

For example, a refractive error caused by strabismus or astigmatism can be corrected with eyeglasses. Otherwise, treating amblyopia essentially involves forcing the brain to recognize and use the affected eye. This can be accomplished by using an eyepatch over the “good” eye, or if the child struggles with the eyepatch, eyedrops (atropine) that blur the vision of that eye may be used for similar effect. It may take months to years to correct the condition, and some children require more treatment as time goes on. Sadly, in some children treatment may be unsuccessful. Finally, every child should have a complete eye exam between ages three to five.

For more information go to the National Eye Institute at: 

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 By Peter Galvin, MD

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