Vitrectomy is an effective treatment for proliferative diabetic retinopathy, and most patients are able to stabilize their vision as a result. However, intraoperative neovascular hemorrhage is a major unavoidable nuisance of the procedure, severely affecting the visual field, prolonging the surgery, and even predisposing to serious surgical complications. Anti-VEGF (neovascular growth factor) treatment with vitrectomy can shrink the retinal neovascularization, reduce intraoperative bleeding, shorten the operation time, and improve the prognosis of the operation. However, the timing of surgery after drug injection is also important. After anti-VEGF treatment, the concentration of VEGF in the vitreous cavity decreases and the concentration of CTGF (connective tissue growth factor) increases relatively, and fiber proliferation starts to be active while the neovascularization is atrophied. After a long time, the fibroproliferation will be more serious, causing increased surgical difficulty. Therefore, it is best to operate as soon as possible after anti-VEGF treatment, with 3 days to 10 days being the best time.