Amblyopia

Amblyopia (also called "Lazy Eye") is the most common cause of decreased vision in children. It occurs when one eye, either because it is more out of focus than the other (because of a refractive error such as myopia, hyperopia or astigmatism) or the two eyes are misaligned.  The brain, rather than having to fuse a very different image from each eye into one image as is done normally, chooses the best image.  The image from the worst eye is ignored, and after a period of time, even if corrective lenses or surgery is used to try to correct the poorer eye, if it is not done soon enough in childhood, the individual loses the ability for normal vision in the eye, and the condition of amblyopia ex anopsia (loss of vision from disuse) develops.  This website, provided by the National Institute of Health, discusses causes, treatments and studies concerning this condition.