Antiangiogenic shift in vitreous after vitrectomy in patients with proliferative diabetic retinopathy

PURPOSE. We determined whether the concentrations of VEGF, erythropoietin, and endostatin in the vitreous are altered after vitrectomy in patient with proliferative diabetic retinopathy (PDR). METHODS. We measured the levels of VEGF, erythropoietin, and endostatin by sandwich ELISA in vitreous samples collected from 38 eyes of 33 patients with PDR before pars plana vitrectomy (without IOL implantation) and the same 38 eyes during IOL implantation 3.1 to 25.7 (mean 6.7) months after the initial vitrectomy. RESULTS. The mean vitreous levels of VEGF (964.5 pg/mL) and erythropoietin (1359.5 pg/mL) in the samples collected before vitrectomy were significantly higher in patients with PDR than in the control patients (0.68 and 70.7 pg/mL, respectively; P < 0.01). The levels of VEGF (292.5 pg/mL) and erythropoietin (557.9 pg/mL) in the samples from eyes with PDR collected at the time of IOL implantation were significantly lower than those collected before vitrectomy (P < 0.01). In contrast, the changes in the level of endostatin were not significant after vitrectomy. The VEGF and erythropoietin levels in the vitreous fluid from patients with PDR were correlated inversely with the interval between the initial vitrectomy and the time of the IOL implantation. CONCLUSIONS. The significant decrease in the intravitreal concentration of VEGF and erythropoietin, and an absence of a significant change in the endostatin indicated a shift in the antiangiogenic balance in the vitreous of patients with PDR after successful vitrectomy.