Participants have a complete eye examination once a year and are contacted at least once a year between visits to check on their status. The eye examination includes measurement of visual acuity (vision chart test) and examination of the inside of the eye after the pupils have been dilated with eye drops. Photographs of the inside of the eye may be taken using a special camera that flashes a bright light in the eye. A blood sample may be obtained to test for cholesterol level and genes related to inflammation.