Ashok V Katta1, R V Katkam, H Geetha. 1. Assistant Professor, Department of Biochemistry, Dhanalakshmi Srinivasan Medical College , Perambalur, Tamil Nadu, India .
Abstract
BACKGROUND: Cataract is one of the major causes of a visual impairment, which eventually leads to blindness. An oxidative damage to the lens proteins is a major factor which leads to cataract formation. Therefore, we intended to study the relationship between the biochemical markers of oxidative stress and various forms of cataracts. METHODS: We examined the lenses and the sera of 120 subjects who were aged 50 to 80 years, who were distributed in two groups, viz. the study group (90 patients) and the control group (30 subjects). The oxidative stress was assessed by estimating the lipid peroxidation product in the form of thiobarbituric acid reactive substances (TBARS), the antioxidant status by measuring the levels of vitamin E and the total antioxidant capacity (TAC). The study group patients were further divided into those with nuclear cataracts (30 patients), cortical cataracts (30 patients), and diabetic cataracts (30 patients). RESULTS: In this study, it was found that the levels of TBARS in the study group were significantly high (p<0.001), whereas the TAC (p<0.001) and the vitamin E (p<0.001) levels were significantly low, both in the lenses and the blood of the study group as compared to those of the control group. CONCLUSION: Thus, the present study suggests that an imbalance between the oxygen free radicals and the antioxidants may lead to lipid peroxidation in the lens. Also, the elevated levels of glucose in the diabetic cataracts lead to the auto-oxidation of glucose and a non-enzymatic glycation of the lens protein. Thereby, the high molecular weight proteins aggregate in the cataract.
BACKGROUND:Cataract is one of the major causes of a visual impairment, which eventually leads to blindness. An oxidative damage to the lens proteins is a major factor which leads to cataract formation. Therefore, we intended to study the relationship between the biochemical markers of oxidative stress and various forms of cataracts. METHODS: We examined the lenses and the sera of 120 subjects who were aged 50 to 80 years, who were distributed in two groups, viz. the study group (90 patients) and the control group (30 subjects). The oxidative stress was assessed by estimating the lipid peroxidation product in the form of thiobarbituric acid reactive substances (TBARS), the antioxidant status by measuring the levels of vitamin E and the total antioxidant capacity (TAC). The study group patients were further divided into those with nuclear cataracts (30 patients), cortical cataracts (30 patients), and diabetic cataracts (30 patients). RESULTS: In this study, it was found that the levels of TBARS in the study group were significantly high (p<0.001), whereas the TAC (p<0.001) and the vitamin E (p<0.001) levels were significantly low, both in the lenses and the blood of the study group as compared to those of the control group. CONCLUSION: Thus, the present study suggests that an imbalance between the oxygen free radicals and the antioxidants may lead to lipid peroxidation in the lens. Also, the elevated levels of glucose in the diabetic cataracts lead to the auto-oxidation of glucose and a non-enzymatic glycation of the lens protein. Thereby, the high molecular weight proteins aggregate in the cataract.
Entities:
Keywords:
Cataract; Lens; Lipid peroxidation; Protein glycation; Total antioxidant status; Vitamin E