Superoxide dismutase in the anterior chamber and the vitreous of diabetic patients.

Total superoxide dismutase (SOD) activity was examined in the anterior humor of 32 diabetic patients and 34 nondiabetic controls during cataract extraction. Median age (95% confidence interval) was 77.5 yr (73.3-81.0) and 79.3 yr (76.0-83.2), respectively. The SOD activity also was examined in posterior vitreous sampled peroperatively in 10 diabetics with proliferative retinopathy and post-mortem in seven diabetic patients and 35 nondiabetic controls. Ages were 57.2 yr (35.0-73.9), 74.4 yr (40.7-83.6), and 73.8 yr (65.0-80.2), respectively. In nondiabetic patients, the total SOD activity was much lower in the anterior chamber, 9.9 U/ml (8.1-12.6), than in the posterior vitreous, 106.3 U/ml (range 65.6-119.0), P < 0.001. We found no difference between the SOD levels in the anterior chamber of nondiabetic controls and diabetic patients, who had 9.6 U/ml (7.6-13.7). The SOD activity in posterior vitreous in diabetic patients sampled peroperatively, 23.9 U/ml (8.9-39.2), P < 0.0001, and post-mortem, 39.5 U/ml (6.5-214.2), P < 0.04, was significantly lower than in the controls sampled post-mortem, 106.3 U/ml (65.6-119.0). Low levels of SOD in the anterior chamber may be involved in cataract development, in diabetic patients and nondiabetic controls. That diabetics had decreased SOD activity in the posterior vitreous points to a possible role of SOD in the complex process of diabetic retinopathy development.