NASA Study Of Cataract In Astronauts (NASCA). Report 1 : Cross-sectional study of the relationship of exposure to space radiation and risk of lens opacity - Chylack, Leo T. Jr.; Cucinotta, Francis A.; Feiveson, Alan H.; Hardy, Dale S.; Manuel, F. Keith; Marak, Lisa J.; Peterson, Leif E.; Tung, William H.; Wear, Mary L.