Vitreoretinal surgery for epiretinal proliferation tractional retinal detachment associated with proliferative diabetic retinopathy (PDR) is often complicated by hemorrhage from fibrovascular tissue. To control the bleeding during tissue dissection multiple measures and techniques are used.

Bevacizumab is an anti VEGF antibody which has been used to induce regression of ocular neovascularization. Its intraocular injection has been increasingly used for treatment of choroidal neovascularization (CNV) associated with age related macular degeneration (AMD) with fairly good success.Also it has been shown to be effective for treatment of PDR complicated with vitreous hemorrhage and iris neovascularization. We hypothesized that if anti-angiogenic agents, such as bevacizumab are injected into the vitreous cavity before vitrectomy in cases of PDR; there may be partial regression of neovascularization resulting in less intraoperative (and postoperative) hemorrhage. This can make the operation easier and shorter and lessen the need for intraocular cautery..

In this study diabetic patients who are candidated for vitrectomy with similar complexity scores will be randomized to preoperative injection or no injection of 2.5 mg Bevacizumab .In the injection group, 2.5 mg of bevacizumab (0.1 ml of commercially available Avastin vial, Genentech, inc. South San Francisco, CA) will be injected into the vitreous 3-5 days before operation.

During each operation, the number of endodiathermy applications, backflush needle applications and the duration of surgery will be recorded by an independent observer. Also, type of tamponade, post operation vitreous hemorrhage and 3 months postoperative visual acuities wil be recorded. all these parameters will be compared in two groups.