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Definition of Lazy Eye (Amblyopia)
Amblyopia is most common in children.
The impairment often develops when there are circumstances that allow one eye to become dominant in sending nerve impulses to the brain, such as strabismus (the inability of the eyes to focus on the same object) or congenital cataracts (opacity of the lens).
Amblyopia can also develop when there is significant disparity in the refractive capabilities of the eyes, such as when one eye is hyperopic (farsighted) or myopic (nearsighted) and the other eye has normal vision.
The brain becomes accustomed to messages the dominant eye and “ignores” nerve signals from the nondominant, or “lazy,” eye. Untreated amblyopia can result in permanent vision impairment or legal blindness.
The diagnostic path includes close examination of the eyes to determine whether other disease processes are present that might account for the vision deficit. Treatment targets those processes, such as cataracts or refractive errors, when they exist.
When the eye is otherwise healthy and normal, treatment consists of forcing the brain to rely on the amblyopic eye, usually by patching the dominant eye for structured periods of time.
Sometimes the ophthalmologist will substitute atropine drops in the eye, which dilate the pupil and distort the eye’s ability to focus, when a child refuses to wear an eye patch or an eye patch is otherwise not the most appropriate therapeutic choice. The dilation interferes with the eye’s ability to focus, forcing the brain to interpret nerve messages from the untreated eye.
When detected and treated in children who are under age 9, most amblyopia responds to treatment and vision returns. Delayed or inadequate treatment may result in permanent dysfunction of the eye–brain pathways, as these become entrenched by age 9 or 10. After this time the vision pathways are well established and amblyopia can no longer develop.