OBJECTIVE: To describe the prevalence across time of 3 chronic eye diseases among a representative cohort of elderly subjects. STUDY DESIGN: Longitudinal observation of Medicare claims. Population A random sample of Medicare beneficiaries 65 years and older, nationally representative at baseline. MAIN OUTCOME MEASURES: Diagnosis of diabetic retinopathy, glaucoma, and age-related macular degeneration. METHODS: Beneficiaries were followed from 1991 to 1999 unless mortality or enrollment in a health maintenance organization for 6 or more months in a year intervened. Claims data were analyzed for the presence of codes from the International Classification of Diseases, Ninth Revision, Clinical Modification, indicating 1 of the 3 conditions. Transitions between severity stages were also evaluated. RESULTS: Of 20 325 beneficiaries in 1991, 10 476 were available for analysis in 1999. The prevalence of diabetes mellitus increased from 14.5% in 1991 to 25.6% by 1999, with diabetic retinopathy among persons with diabetes mellitus increasing from 6.9% to 17.4%. Primary open-angle glaucoma increased from 4.6% to 13.8%. The percentage of glaucoma suspects increased from 1.5% to 6.5%, as did the percentage of narrow-angle glaucoma (0.7%-2.7%). The prevalence of age-related macular degeneration increased from 5.0% to 27.1%. Overall, the proportion of subjects with at least 1 of these 3 diseases increased from 13.4% to 45.4%. CONCLUSIONS: The clinical diagnosis of major chronic eye diseases associated with aging increased dramatically in a longitudinal sample. At the end of 9 years, nearly half of the surviving Medicare beneficiaries had at least 1 of these diseases.