HUMAN DIABETIC CATARACT - ROLE OF LIPID-PEROXIDATION

To test whether impaired glutathione redox status may be related to le ns oxidative damage in humans, we measured glutathione (total and oxid ised forms) and malondialdehyde, a lipid peroxidation product, in clea r lenses and diabetic and non-diabetic cataracts. Diabetic cataracts w ere divided into 2 subgroups with either intact or abnormal haemo-ocul ar barrier as evaluated by preoperative iridography. Decreased total g lutathione values were observed in cataractous (diabetic and non-diabe tic) as compared to clear lenses (p < 0.001), whereas enhanced oxidise d glutathione levels were found in diabetic caracts as compared to non -diabetic ones and clear lenses (p < 0.001). Malondialdehyde concentra tions were significantly higher in all types of cataracts, especially myopic and diabetic ones, than in clear lenses (p < 0.001). Moreover, malondialdehyde levels in diabetic lenses were inversely correlated wi th total glutathione (r = -0.80; p < 0.001) and linearly correlated wi th oxidised glutathione values (r = 0.76; p < 0.001). Finally, glutath ione redox status was found to be more seriously impaired in lenses fr om diabetic patients with abnormal than intact haemo-ocular barrier. T hese data suggest a contributory role of lipid peroxidation and glutat hione oxidation and consumption in the pathogenesis of cataract, espec ially in diabetic lenses with haemo-ocular barrier abnormality.