By the way, doctor: What can I do to prevent cataracts?

Q. Is it true that cataracts are made of calcium? Can I do anything to avoid getting a cataract? What about diet?

A. A cataract is a vision-clouding area in the lens of the eye. About half of all people ages 65 to 74, and 70% of those ages 75 and over, develop cataracts, which are the leading cause of blindness worldwide. Fortunately, surgery is safe and effective; in places like the United States, where it's one of the most common operations performed, it leads to improved vision in about 90% of cases.