Eye cataract: A clouding of the lens of the eye. The normally clear aspirin-sized lens of the eye starts to become cloudy. The result is much like smearing grease over the lens of a camera. It impairs normal vision.
There are many causes of cataracts including cortisone medication, trauma, diabetes, many other diseases and simply aging. Cataracts will affect almost all people if they are fortunate enough to live long enough.