Influence of retinal coagulation status on retinal oxidative metabolites and VEGF level in 208 patients suffering from proliferative diabetic retinopathy

Background: Oxidative metabolites and different cytokines are believed to be involved in the pathogenesis of (proliferative) diabetic retinopathy. It was the aim of this study to analyze vitreous body and proliferations of diabetic patients for oxidative metabolites and VEGF und to correlate these values to the retinal coagulation status. Patients and Methods: The study was performed in 208 patients vitrectomized for diabetic retinopathy (Type I: n = 114, Type II: n = 94). Grouping of patients was performed according to retinal coagulations status: (1) no or minimal preoperative coagulation [mean coagulation area, CA: 156 mm(2)], (2) coagulation (scatter laser coagulation und/oder cryopexy) < 3 months before surgery [CA: 589 mm(2)]. (3) coagulation > 3 months before surgery [CA: 546 mm(2)]. In the vitreous body and, if present, in the fibrovascular proliferations (Type I: n = 83; Type II: n = 73) the level of lipid peroxides (LPO, measured with two methods) and VEGF was determined. Results: In the vitreous body LPO in group 1 were significantly (P < 0,01 (Type I und II)) higher as compared to other groups. In group 3 LPO were significantly lower as compared to group 2 (P < 0.01 (Typ I) and P < 0.05 (Typ II)). Similiar results were observed in the proliferations. In Type I patients VEGF values were significantly (P(0.01 for group 1 vs. 2 and groups 1/2 vs. 3) reduced following coagulation and coagulation + 3 months. In Type II patients only group 3 was significantly (Ps 0.01) different from group 1. In proliferations groups 2 and 3 were significantly different from group 1 (P(0.05 for Typ I and Type II patients). Conclusions: The time course of the values leads to the conclusion;that oxidative metabolites are able to directly modulate growth activity and to exert this effect via induction of VEGF. This hypothesis has to be confirmed in vitro and by means of a prospective study.