Comparative Analysis of Oxidative Stress Biomarkers in 50 Primary Open-Angle Glaucoma Patients

BACKGROUND Glaucoma, a leading cause of irreversible blindness, is associated with increased oxidative stress and impaired antioxidant defense mechanisms. This study compared serum levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) in 50 patients with primary open-angle glaucoma (POAG) and 52 healthy controls. MATERIAL AND METHODS Fifty patients in the POAG group and 52 age- and sex-matched individuals in the control group were included in the study. SOD activity was evaluated using the optical density of the blue formazan dye formed at 560 nm due to the interaction of nitroblue tetrazolium with xanthine and superoxide radicals generated by xanthine oxidase. CAT activity in serum was assessed using hydrogen peroxide and phosphate buffer solution. Measurement of GSH levels was performed using a phosphate buffer and DTNB (Ellman's reagent) solution. MDA levels were quantified by measuring the colored complex formed with thiobarbituric acid. All biomarkers were measured using spectrophotometric methods. RESULTS The results indicated significantly higher serum MDA levels (P<0.001) and CAT levels (P<0.001), along with lower SOD levels (P<0.001) and GSH levels (P<0.001) in patients with POAG compared to the controls. CONCLUSIONS These findings suggest that POAG patients experience increased oxidative stress and have an insufficient antioxidant defense system. The imbalance in the oxidant-antioxidant equilibrium in POAG patients suggests a role of oxidative stress in pathogenesis of the disease. Evaluating serum levels of these biomarkers could be valuable for diagnosing and treating POAG.