A cataract is a clouding of the naturally transparent lens of the eye that can occur as one ages. Natural proteins in the lens clump together and can cloud the eye. The National Eye Institute says most cataracts develop with age, as more than half of all Americans age 80 or older either have cataracts or have had surgery to remove them. But cataracts can occur for other reasons, such as after an eye injury or after surgery for another vision problem.
