To investigate the risk factors of postoperative vitreous hemorrhage (PVH) after vitrectomy for proliferative diabetic retinopathy (PDR).

A case-control study was conducted.A total of 1 848 consecutive PDR patients (1 848 eyes) with vitreous hemorrhage receiving first pars plana vitrectomy (PPV) in Tianjin Medical University Eye Hospital from June 2012 to May 2019 were enrolled.There were 979 males and 869 females, with the average age of (55.72±10.39) years.All of the enrolled eyes underwent standard three-channel PPV.The subjects were followed up for 6 to 24 months, with the mean follow-up of (379.34±231.28) days.The eyes were divided into PVH group and non-PVH group according to whether the PVH occurred or not.The PVH group were further divided into early PVH group and late PVH group according to the occurrence time of PVH.There were 170 (9.19%) of 1 848 eyes developed PVH after surgery, including 17.64%(30/170) of eyes with early PVH and 82.36% (140/170) of eyes with late PVH.The PVH occurred at 6 to 450 days after surgery.Baseline systemic parameters including sex, age, diabetes duration, preoperative glycosylated hemoglobin (HbA1c) level, and ocular parameters including whether or not performing panretinal photocoagnlation, whether or not receiving treatment of anti-vascular endothelial growth factor (VEGF) three days before operation, lens status, whether or not being combined with neovascularization of iris (NVI), as well as intraoperative ocular parameters including whether or not having neovascularization of disc (NVD) bleeding, whether or not being combined with cataract phacoemulsification, whether or not receiving postoperative anti-VEGF, were analyzed by multivariate logistic regression analysis to identify the risk factors of PVH after PPV in PDR patients with VH.This study adhered to the Declaration of Helsinki, and the study protocol was approved by an Ethics Committee of Tianjin Medical University Eye Hospital (No.2019KY[L]-09).

Multivariate logistic regression analysis revealed that age (OR=0.940, P<0.01), preoperative high HbA1c level (OR=1.878, P<0.01), combined with retinal vein occlusion (RVO) (OR=8.310, P<0.01), diabetes diet to control blood glucose (OR=3.030, P<0.01), diabetes duration (OR=1.044, P<0.01), history of hypertension (OR=1.802, P<0.01), nephropathy or cardiovascular or cerebrovascular diseases (OR=18.377, P<0.01), preoperative NVI (OR=7.488, P<0.01), not combined with phacoemulsification surgery (OR=1.628, P=0.023), NVD bleeding (OR=2.691, P<0.01), postoperative anti-VEGF treatment (OR=0.181, P<0.01), postoperative air tamponade (OR=1.901, P=0.024) were associated with PVH.There were no significant differences in baseline, ocular and intraoperative ocular parameters between early PVH and late PVH groups (all at P>0.05).

Younger age, preoperative high HbA1c level, combined with RVO, diabetes diet to control diabetes, diabetes duration, history of hypertension, nephropathy or cardiovascular or cerebrovascular diseases, preoperative NVI, uncombined with cataract surgery, NVD bleeding, without postoperative intravitreal anti-VEGF injection, postoperative air tamponade are the potential risk factors of PVH after PPV for PDR patients with VH.

Proliferative diabetic retinopathy/surgery; Pars plana vitrectomy/adverse effects; Postoperative vitreous hemorrhage/etiology