The data are the mean±SD (group I, n=6 lenses; other groups, n=12 lenses at each time). The activity of GR is expressed as μmol per gram protein. At all stages, the mean values for all diabetic groups were less than the normal group, but there were no significant differences between all five groups at various stages. Group I: normal; II: NAC-treated (0.1 mg/ml); III: NAC-treated (0.5 mg/ml); IV: GSH-EE-treated (1 mg/ml); V: untreated diabetic.