While the exact cause of cataracts is unknown, experts believe that oxidative stress damages certain enzymes and proteins in the eye’s natural lens, which causes the lens to become cloudy.

And though some research has produced conflicting results, eating a healthy diet rich in antioxidants and certain vitamins has been shown in several studies to be associated with a reduced risk of cataracts or their progression.

http://www.allaboutvision.com/nutrition/cataracts.htm