Recent findings have upheld the hypothesis that environmental UV-radiation is a factor that contributes to human cataract formation. Our objectives are to study how environmental UV-exposure enhances cataractous changes in the lens and to explore conditions whereby antioxidants inhibit these changes. We will study squirrel and rabbit lenses in vitro, and their epithelial cells in culture. The results of parallel studies on fresh human intracapsularly extracted cataracts and eye bank lenses will be compared with those of animal data. How relevant the defects produced in animal lenses are to those of human aged and cataractous lenses will be assessed. The UV damages to be investigated are: lens epithelial cell anomalies, breakdown of F-actin, loss of ATP, oxidation of -SH groups, reduced activities of NA-K-ATPase, catalase, glutathione reductase, su- peroxide dismutase, DNA repair enzymes, and DNA single-strand breaks. Lens cell uptake of these antioxidants will be measured. We will compare photo- chemical changes in pure macromolecules and protection by these antioxidant with in vitro and cell culture data. Methods of analysis to follow UV-exposure are: immuno and histochemistry and histology, dye-binding, electron microscopy, biochemical assays of enzymes, ATP determination (by NMR), SH and SS determination, cell growth and survival, DNA strand breaks and characterization of lens epithelial cell DNA repair enzymes, protein analysis by gel isoelectric focusing HPLC, PAGE and immuno-blotting; loss of O2 from media. We hope to test biologically compatible chemical antioxidants to retard oxidation-related cataract formation.