A cataract is a cloudy area in the lens of the eye. A normal lens is clear. It lets light pass to the back of the eye. A cataract blocks some of the light. As a cataract develops, it becomes harder for a person to see.
Cataracts are a normal part of aging.
About half of Americans ages 65 to 74 have cataracts. About 70 percent of those age 75 and over have this condition. Most people with cataracts have a cataract in both eyes. However, one eye may be worse than the other because each cataract develops at a different rate. Some people with ca ataract don't even know it.