No one knows for sure why the eye's lens changes as we age, forming cataracts. Many studies suggest that exposure to ultraviolet light is associated with cataract development, so ophthalmologists recommend wearing sunglasses and a wide-brimmed hat to lessen your exposure.

Other studies suggest people with diabetes are at risk for developing a cataract. The same goes for users of steroids, diuretics and major tranquilizers, but more studies are needed to distinguish the effect of the disease from the consequences of the drugs themselves.

Some ophthalmologists believe that a diet high in antioxidants, such as beta-carotene (vitamin A), selenium and vitamins C and E, may forestall cataract development. Meanwhile, eating a lot of salt may increase your risk.

Other risk factors include cigarette smoke, air pollution and heavy alcohol consumption.