A cataract classification and grading system for the main purpose of cataract epidemiological studies is proposed by the Japanese Cooperative Cataract Epidemiology Study Group. Cataractous types are classified principally into cortical, nuclear and subcapsular opacities. Stages of cataract advancement are classified into grade I (early stage), grade II (moderate stage) and grade III (advanced stage). Regarding cortical opacities an opacified area obtained from red-reflex images is utilized for grading judgment. Nuclear opacity grading is based on the intensity of scattering at the nucleus. Grading of subcapsular opacities is judged from their extension in the three different pupillary areas. To help grading judgments, standard pictures of cortical and nuclear cataracts are provided. Gradings of lens coloration are divided into pale yellow (grade I), yellow (II), brownish yellow (III) and brown including reddish and black brown (IV). A recording chart is also provided.