A cataract is a cloudy area in the lens of the eye. The lens helps focus light on the retina at the back of the eye. As a cataract grows larger over time, the cloudiness worsens and causes vision problems.
Most cataracts occur naturally as people get older.
Cataracts don't spread from one eye to the other, but many people have cataracts in both eyes. Cataracts do not cause complete blindness. However, it is possible to lose enough vision to be declared legally blind. The symptoms of a cataract develop slowly and are painless. The condition may go unnoticed and undiagnosed for a long time.