Postoperative vitreous hemorrhage is a common complication after vitrectomy for proliferative diabetic retinopathy. There have been efforts to lower the incidence of postoperative vitreous hemorrhage such as preoperative bevacizumab injection. Bevacizumab (Avastin) is a potent inhibitor of angiogenesis and has been shown to decrease retinal and iris neovascularization in proliferative diabetic retinopathy. Recently there have been reports showing that preoperative bevacizumab injection could reduce intraoperative bleeding from abnormal vessels and could make surgery easier and more successful. Our hypothesis is that intraoperative bevacizumab injection could reduce postoperative vitreous hemorrhage by inhibiting the vessel formation after surgery.

We started the prospective randomized comparative study to determine the effect of pre and intra-operative bevacizumab injection on postoperative vitreous hemorrhage after diabetic vitrectomy in comparison to vitrectomy without any adjuvant drug.

Inclusion Criteria:

• patients undergoing first vitrectomy for vitreous hemorrhage secondary to proliferative diabetic retinopathy

Exclusion Criteria:

• follow-up period of less than 3 months
• not first vitrectomy
• abnormal blood coagulation
• uncontrolled hypertension