Background: Age-related macular degeneration (AMD) is an eye disease. It is the leading cause of vision loss in people over 55 in the U.S. Changes in the eye can make it difficult for the eye to adjust to low light. This is known as dark adaptation. Identifying and watching the early to middle stages of AMD and changes in dark adaptation might help researchers develop new treatments to stop the disease before it becomes severe. Taking vitamin A might help improve vision in people with AMD. Objectives: To see if taking 16,000 IU of vitamin A per day improves vision in people with AMD. Also to improve understanding of AMD and associated dark adaptation. Eligibility: Adults ages 50 and older with AMD and normal liver function Design: Participants will be screened with: Medical and eye disease history Eye exam: The pupil will be dilated with eye drops. Pictures will be taken of the retina and the inside of the eye. Including the screening visit, participants will have at least 5 visits. They will be about once a month over 6 months. Visits include: Questions about eye problems in certain light Eye exam Blood and urine tests Dark adaptation protocol: Participants will sit at a machine in a dark room. They will look into the machine and push a button when they see a light. This lasts 20-30 minutes. Participants will take a vitamin A supplement by mouth once a day for 2 months. They will record when they take the pills in a diary.
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Change in Dark Adaptation Rod Intercept Time (RIT) From Baseline in the Study Eye at the Treatment Completion Visit (Month 2 for Cohort 1 and Month 1 for Cohort 2)
Timeframe: Baseline to Month 2 for Cohort 1 and Baseline to Month 1 for Cohort 2