[Peroxidative reactions in the vitreous as related to diabetic retinopathy]

The blood of diabetics often shows enhanced peroxidative reactions and non-enzymatic glycosylation, or glycation. These features should also be manifest in the vitreous in diabetic eyes. I quantitated the level of superoxide dismutase (SOD) in the serum and the vitreous in 22 eyes of 23 diabetics and in 16 eyes of 16 nondiabetics. The total amount of serum SOD was the same in both groups. There was a significant decrease in SOD activity in the diabetic vitreous (p < 0.05). The diabetic vitreous also showed increases in glycated Cu, Zn-SOD and glycated protein. The level of lipid peroxidases was significantly increased in the diabetic vitreous (p < 0.05). These findings suggest that glycation is enhanced in the diabetic vitreous resulting in collapse of active oxygen scavenging and in progressed peroxidation.