Lazy eye affects about two to three out of every 100 children in the U.S., and it's not as easy to notice as you'd think.
A patient with amblyopia (or lazy eye) has a high asymmetry in the prescription between the two eyes and that causes one eye to have decreased vision from disuse, says Paul J. Lederer, MD, developmental optometrist in private practice in the Chicago suburbs. There are few, if any, signs of amblyopia, which makes it difficult to detect. The form of lazy eye that's easier to identify is called strabismus, and it occurs when the eye drifts or wanders inward or outward constantly or intermittently. It's easier for parents to spot because they can see that the eyes are misaligned. Lazy eye typically affects only one eye, but can sometimes affect both. Eye doctors recommend children get their vision screened as early as six months old to detect any issues. "After about the age of four months or so, if the eye is not lining up properly, it's not normal. It should be looked at," says David Epley, MD, owner of Children's Eye Care in Kirkland, Washington.