Classification of human cataractous change by the American Cooperative Cataract Research Group method.

The American Cooperative Cataract Research Group (CCRG) has adopted a system of classifying cataractous changes in excised human cataracts that is based on separate and independent photographic documentation of opacification and nuclear colour. The classification data can be simplified according to the needs of the scientist in his or her effort to measure clinically or scientifically significant associations between laboratory measures and cataractous change. The association between nuclear colour and the extent of cortical opacification and the intensity of nuclear opacification has been studied and found to be insignificant. These results justify the recommendation that nuclear colour be abandoned as the single index of severity of any type of senile cataractous change. The adaptability of this system to in vivo use in epidemiological and other studies of the natural history of cataractous change is discussed. Its limitations are outlined. The system may offer a basis for international cooperation in cataract classification.