Abstract
PURPOSE: The main factor that causes cataracts is the increased oxidative stress and imbalance of an antioxidant defense mechanism, which leads to significant changes in the lens microarchitecture. Senile cataract is the most common type of acquired cataracts due to aging. METHODS: We carried out a case-control study in the biochemistry department to examine the antioxidant status (catalase and total antioxidant capacity [TAC]) and lipid peroxidation marker, that is, malondialdehyde (MDA) in human lens epithelial cells (HLECs) of different grades of senile cortical, nuclear, and posterior subcapsular cataracts. We collected 150 samples from patients aged 50-90 years. These included 50 samples of cortical cataracts, 50 of nuclear cataracts, and 50 samples of posterior subcapsular cataracts. We measured catalase activity by the Beer method, TAC by the Benzie and Strain method, and protein by the Bradford method. We also estimated TAC in the aqueous extract of HLECs by the ferric reducing ability of plasma (FRAP) method and MDA by the thiobarbituric acid assay method. RESULTS: The results of this study showed that the level of catalase enzyme was higher in the first grade of nuclear, posterior subcapsular, and cortical cataracts than in other grades. This suggests that the catalase enzyme activity drops sharply in the second and third grades of these types of cataracts. The same pattern was observed for TAC, which was higher in the first grade of nuclear, posterior subcapsular, and cortical cataracts than in other grades. There were significant differences between catalase and TAC in different grades of cataracts, indicating that as the grading increases, both catalase and TAC decrease. CONCLUSION: The results of this study showed that the levels of MDA were higher and the levels of catalase and TAC were lower in patients with more severe cataracts compared to the healthy controls.