Age-related cataracts: scope of problem and prospects for prevention.

Cataracts develop in the lens of the eye which is responsible for focusing incoming light onto the retina. Early in life the lens is transparent, and incoming light encounters no difficulty in its passage through the eye. With aging, the lens becomes less clear, incoming light is scattered to an increasing degree, and if loss of lens clarity is severe enough, vision is affected. When clouding of the lens impairs vision, a clinically significant cataract is present. Currently there is no medical treatment for age-related cataract. The only treatment is surgical removal of the affected lens when vision is sufficiently impaired. A major goal of past and on-going epidemiologic studies is the identification of risk factors for cataract, so that strategies for the prevention of cataract can be developed.