The purpose of the study is to collect information on the prevalence and incidence of age-related cataract, macular degeneration and diabetic retinopathy, all common eye diseases causing loss of vision in an aging population. The study was designed to discover (or detect) causes of these conditions. The study has also examined other aging problems, such as decline in overall health and quality of life and development of kidney and heart disease.

Approximately 5000 subjects participated in the baseline examination between 1988 and 1990. Five-, 10-, 15-, and 20-year follow-up examinations have taken place, with each phase involving, respectively, 3700, 2800, 2100, 2000, and more than 1900 participants.