ObjectiveTo investigate the risk factors of postoperative vitreous hemorrhage after minimal vitrectomy without endotamponade for proliferative diabetic retinopathy (PDR).MethodsFrom June 2015 to June 2017, 103 eyes of 103 patients with PDR diagnosed and underwent minimalvitrectomy in Henan Provincial People's Hospital were enrolled in the study. There were 58 males and 45 females, with the average age of 58.37±10.14 years and diabetes duration of 8.7±7.2 years. Baseline systemic parameters including sex, age, diabetes duration, hypertension, HbA1c, creatinine, whether received anticoagulants, ocular parameters including whether combined with vitreous hemorrhage, whether finished panretinal photocoagulation (PRP), whether received treatment of anti-VEGF, whether combined with iris neovascularization (NVI), lens status preoperatively, whether hypotony postoperatively and intraoperative parameters including whether disc neovascularization (NVD) bleeding, whether fibrovascular membrane (FVM) residual, laser points, whether combined with cataract phacoemulsification were identified by multivariate logistic regression analysis.ResultsTwenty-nine of 103 eyes (28.15%) developed PVH in 1 day to 6 months after surgery, with self absorption of 18 eyes and reoperation of 11 eyes. Univariate analysis showed there were significant differences in age (t=2.124, P=0.036), anti-VEGF(χ2=7.105, P=0.008), NVD bleeding (χ2=10.158, P=0.001) and FVM residual(χ2=8.445, P=0.004) between patients with and without postoperative vitreous hemorrhage. Sex (χ2=0.021, P=0.884), diabetes duration (t=0.87, P=0.386), hypertension (χ2=2.004, P=0.157), HbA1c (t=1.211, P=0.229), creatinine (t=0.851, P=0.397), preoperative oral anticoagulants (χ2=0.985, P=0.321), preoperative vitreous hemorrhage (χ2=0.369, P=0.544), PRP (χ2=1.122, P=0.727), NVI (χ2=2.635, P=0.105), lens status (χ2=0.172, P=0.679), hypotony postoperatively (χ2=1.503, P=0.220), laser points (χ2=1.391, P=0.238) and combined phacoemulsification surgery (χ2=0.458, P=0.499) were not associated with PVH. Multivariate logistic regression analysis revealed the more PVH appeared in younger (OR=1.065, P=0.009) and NVD bleeding (OR=6.048, P=0.001) patients.ConclusionYounger age and NVD bleeding are the important risk factors for PVH after minimal vitrectomy without endotamponade in PDR.