简介：AbstractBackground:Proliferative diabetic retinopathy (PDR) is a progressive stage of diabetic retinopathy featured by the formation of neovascular and proliferative membrane. Vascular endothelial growth factor (VEGF) acts as a pivot factor in the development of neovascularization. This study was to investigate the changes of intravitreal VEGF concentrations of severe PDR after intravitreal injection of conbercept (IVC) and its potential advantages to the following vitrectomy.Methods:This was a prospective, interventional, randomized controlled study. Sixty eyes (60 patients) with severe PDR and 20 eyes from 20 patients with rhegmatogenous retinal detachment complicated with proliferative vitreoretinopathy were enrolled in this study. PDR eyes were randomly assigned to three groups by sortation randomization method with 20 eyes in each based on the interval of preoperative IVC (group A: 7 days, group B: 14 days, group C: non-IVC). Another 20 eyes without diabetes were enrolled as the non-diabetic control group (group D), receiving PPV directly. Vitreous specimens of all 80 patients were collected and evaluated afterwards. The intravitreal VEGF concentration of the four groups, and the total surgical time and the intraoperative bleeding rate of the PDR groups were recorded.Results:The mean intravitreal VEGF concentrations of groups A-D were 66.6 ± 43.3, 93.1 ± 52.3, 161.4 ± 106.1 and 1.8 ± 1.2 pg/mL, respectively. It increased significantly in PDR patients (groups A, B and C) (P = 0.002, <0.001, and <0.001, respectively). PDR patients with preoperative IVC (groups A and B) presented significantly lower VEGF concentrations (P < 0.001 and 0.001), intraoperative bleeding rates (P= 0.004) and total surgical time (P < 0.001, P= 0.003) compared with group C. No statistical differences were presented between groups A and B on the three parameters.Conclusion:Seven days and 14 days of preoperative IVC are equally efficient and safe for the vitrectomy of severe PDR patients through decreasing vitreous VEGF concentrations, intraoperative bleeding rate and total surgical times.