Clouding of the lens, or cataract formation, accounts for vision loss in about 45 percent of the U.S. population aged 75 to 85 years. Macular degeneration-destruction of the part of the retina responsible for central vision used in reading-is the leading cause of legal blindness in people over 60 years of age.

This 10-year study on age-related macular degeneration and cataract will investigate:

1. The natural course and prognosis of these diseases;
2. The effects of vitamin and mineral supplements on their development and progression; and
3. Risk factors associated with their development.

Patients with age-related macular degeneration or cataract will be evaluated for their eligibility in this study with a medical history, vision test and thorough eye examination, including photographs of the lens and back of the eye. Those accepted to the study will be randomly assigned to take one of the following 4 times a day: 1) a vitamin only; 2) a mineral only; 3) both a vitamin and a mineral; or 4) a placebo (a tablet with no active ingredient). A blood sample will be drawn at the beginning of the study and once a year until its end to measure vitamin and mineral blood levels and to study their effects on cholesterol. Participants will be asked to complete a voluntary questionnaire about their visual function and how it affects their daily lives.

Some patients may be asked to participate in two interviews about 6 months apart, in which they will provide information on their food intake over a 24-hour period. This information will be used to explore possible dietary risk factors for macular degeneration and cataract. Participants may also be asked to provide a small blood sample for use in studying possible hereditary factors associated with age-related macular degeneration. This research may lead to a better understanding of why the condition develops, who is likely to be affected and to what degree, and how to improve treatment.