Cataract and age-related macular degeneration (AMD) are the leading causes of blindness in the older person. Despite the obvious impact on visual impairment, little is known about the impact on functional status of either disease or the possible interaction with co-morbidities. The population based laboratory in core project B will provide a unique opportunity: 1) to measure, at baseline, the contribution of the earliest lens changes and maculopathy to increased risk of functional impairment in mobility, activities and instrumental activities of daily living in 2,300 community- dwelling residents of Salisbury, age 65 to 84; and 2) to determine the impact of progression of lens opacities and maculopathy on change in functional status at the time of 20-month follow-up. The determination of effective preventive or treatment strategies to improve functional status requires the identification of the tasks and activities which are compromised by these diseases. The assessment of the lens and macula of each participant in the community will enable us to carry out etiologic studies of antioxidant status, smoking and alcohol use, and exposure to ultraviolet (UV) and visible light as risk factors and protective factors for cataract and AMD. Our previous studies in this geographic area have demonstrated the importance of high UV exposure on the risk of cortical and posterior sub-capsular cataract, and provide suggestive evidence that visible light exposure is related to AMD. In this project, these findings are extended by proposing high antioxidant status protects against oxidative stress from light exposure, protection which may be attenuated among heavy smokers or drinkers. Cumulative UV and visible light exposure will be assessed using techniques developed by us and validated in this population. Past and current dietary intake of antioxidants will be assessed by interview, as well as biochemistry on blood samples for Vitamins A, C, E, glutathione peroxidase, and zinc. A nested case-control design will be used on the cross-sectional data. A prospective study of antioxidant status and exposure to current UV and visible light and the relationship to incidence and progression of lens opacities and age-related maculopathy will be performed after the 20-month follow-up. This prospective component will provide data on the protective effect of antioxidants and the importance of avoiding sun exposure on the onset or progression of these age-related ocular morbidities.
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