Epidemiology of cataract - a major cause of preventable blindness.

Cataract, or opacity of the lens of the eye, is the most common easily correctable cause of blindness in the world. However, little is known of its prevalence and incidence in different regions, particularly in developing countries, or of the relative importance of the various risk factors. This article describes the available knowledge on the epidemiology of cataract in both developing and industrialized countries, and reviews the methods used to obtain these data. The various predisposing factors, such as diabetes, exposure to radiation, and abnormalities of metabolism, along with the possible mechanisms of cataract formation, are also discussed.