Activity of superoxide dismutase isoenzymes in lens epithelial cells derived from different types of age-related cataract

PURPOSE: To evaluate the level of superoxide dismutase (SOD) and SOD isoenzyme activity in lens epithelial cells (LECs) derived from different types of cataract in patients having phacoemulsification. SETTING: Iladevi Cataract & IOL Research Centre, Memnagar, Ahmedabad, India. METHODS: This observational study of 109 patients having phacoemulsification was performed to evaluate the level of activity in LECs of total superoxide dismutase (TSOD) and 2 superoxide dismutase isoenzymes: copper- (Cu) and zinc (Zn)-dependent SOD (Cu/Zn-SOD) and manganese (Mn)-dependent SOD (Mn-SOD). The curvilinear capsulorhexis (lens capsule) harboring LECs was obtained during phacoemulsification. The anterior lens capsule samples were processed for assaying SOD activity using the nitro blue tetrazolium reduction assay. The samples were grouped based on age and on pure cataract types. RESULTS: The highest level of TSOD, Cu/Zn-SOD, and Mn-SOD activity was in patients 50 years or younger. The activity declined gradually with age (P<.001). The level of TSOD activity increased in cortical cataract. The level of Cu/Zn-SOD and Mn-SOD isoenzyme activity in LECs was higher in cortical cataracts. A significant difference in the level of TSOD and Cu/Zn-SOD activity was found with different types of cataract (P<.001). CONCLUSIONS: The level of TSOD, Cu/Zn-SOD, and Mn SOD isoenzyme activity decreased with age in LECs of patients with age-related cataract. A significant difference in the level of TSOD and Cu/Zn-SOD isoenzyme activity between different types of cataract was observed. The activity of all 3 SOD isoenzymes was highest in cortical cataracts.