Age-related cataract is the main cause of blindness worldwide and is a major reason for visual impairment. Very few data, however, are available on its incidence and progression or the factors related to cataract growth. These data are urgently needed to develop possible control or prevention strategies. The proposed study represents a unique opportunity to obtain these data now in an effective manner by following a subset of the participants in the Lens Opacities Case-control Study (LOCS), an NEI-funded study of cataract risk factors. The LOCS protocol includes Neitz retroillumination, Zeiss slit and Topcon SL photography, as well as an ophthalmologic examination, laboratory testing and a comprehensive interview on risk factors. A follow-up study of LOCS participants thus offers several advantages. First, their lens photographs will serve as a baseline and follow-up photographs will measure cataract growth over time. Second, the large number of nutritional, biochemical, medical, familial, environmental, demographic and ophthalmologic data collected on LOCS cases and controls allows their evaluation as predictors of cataract growth at no additional cost. This application proposes a five-year Natural History of Lens Opacities Study (NHLOS) to: 1) obtain data on the incidence and progression of cortical, nuclear and posterior subcapsular opacities and 2) evaluate risk factors for cataract growth. To achieve these aims, 500 LOCS cases and 300 controls will be followed every nine months for repeated ophthalmologic evaluations and lens photography. Lens photographs will be assessed qualitatively with the LOCS II system of cataract classification to measure incidence and progression rates by type of opacity. Analyses of photographic images will provide quantitative data on progression. The NHLOS will provide, therefore, much needed data on the process and documentation of cataract growth. It will also relate numerous risk factors to subsequent cataract incidence and progression. As such, this study addresses a major need.
