Diabetic retinopathy (DR) is one of the main complications in diabetes, the proliferative diabetic retinopathy (PDR) is the most important one of the reasons leading to decreased vision, PDR is the stage of clinical intervention. Pars plana vitrectomy (PPV) is an effective treatment for PDR, while vitreous haemorrhage (VH) is a common complication after PPV, with incidence ranging from 11.8% to 75%, and is the main cause of reoperation. Anti-Vascular endothelial growth factor (VEGF) therapy for vitreous hemorrhage can inhibit neovascularization and prevent recurrent vitreous haemorrhage after absorption. Previous studies have found that anti-VEGF is a safe and effective treatment for postoperative recurrent VH. In consideration of the psychological and economic factor of patients, this study intends to observe the effectiveness of single vitreous injection of Ranibizumab in the treatment of postoperative recurrent VH on the basis of previous clinical work. Compare the visual acuity, macular thickness, VH recurrence and patient satisfaction between the Ranibizumab group and the PPV group by randomized grouping.To observe the effective rate and clearance time of recurrent VH after Ranibizumab treatment and whether it can effectively reduce the rate of PPV. To provide clinical guidance for the precise treatment of PDR patients, the treatment of PDR patients has important clinical significance and social and economic significance.

1. Patients with proliferative diabetic retinopathy who underwent vitrectomy were collected. Vitreous hemorrhage was completely cleared for more than 1 week after surgery, and vitreous recurrent hemorrhage was not absorbed for more than 4 weeks (grade 2 and above). If the patient has recurrent vitreous hemorrhage or symptoms suggestive of recurrent vitreous hemorrhage, ultrasound at 10mhz posterior segment and 20mhz anterior segment are performed by an experienced sonographer. Patients were randomly assigned to PPV group or Ranibizumab group according to the order in which they came to visit and according to a random number table.
2. PPV group: PPV and pan retinal photocoagulation; in the Ranibizumab group, Ranibizumab was injected and pan retinal photocoagulation was performed during ocular fundus could observed, and observation for 4 weeks. If vitreous hemorrhage was not absorbed/vitreous hemorrhage aggravation/proliferation membrane formation/ retinal detachment, PPV was performed.
3. Collected information: best corrected visual acuity, slit lamp and fundus examination, intraocular pressure, B-ultrasound, macular thickness, the date of recurrent vitreous hemorrhage and treatment, vitreous cleaning time, the time of significant improvement of visual acuity, times and duration of vitreous hemorrhage. The follow-up time was 1 day, 2 weeks, 1 month, 2 months, 4 months and 6 months, respectively. To observe the effectiveness of Ranibizumab in the treatment of postoperative recurrent vitreous hemorrhage and reduce the number of vitrectomy.

Inclusion Criteria:

• Voluntary and able to sign an informed consent form
• Age ≥18 years
• Documented diagnosis of diabetes mellitus (type I or type II diabetes) as defined by the American Diabetes Association or World Health Organization criteria and glycosylated hemoglobin ≤10% within 2 months
• Willing and able to complete all planned visits and evaluations
• Complete Panretinal photocoagulation
• Retinal repositioning
• Complete postoperative vitreous hemorrhage clearance for more than 1 week and non-absorption of recurrent vitreous hemorrhage for more than 4 weeks (grade 2 and above)
• Early postoperative period (1 week to 1 month postoperatively) and delayed postoperative period (4 weeks to 12 months postoperatively)

Exclusion Criteria:

• Patients with less than 6 months of follow-up
• Silicone oil filling
• Other retinal causes of vitreous hemorrhage
• Tractive retinal detachment, pre-retinal proliferative membrane
• Iris redness, neovascular glaucoma
• History of glaucoma
• Ocular inflammation
• Any other intraocular surgery (e.g., corneal transplantation, glaucoma filtration, corneal transplantation therapy, etc.)
• Patients with best corrected visual acuity manual or worse, patients with a single eye
• Previous cerebrovascular or thromboembolic events, hypertensive disorders, renal disease, current use of anticoagulants