El-Batarny break but also may create new retinal breaks (Lee and Abrams 2001). The most common indication for reoperation after diabetic surgery is recurrent vitreous hemorrhage. Approxi- mately 60% of eyes develop recurrent vitreous hemorrhage sometime in the postoperative period (Liggett et al 1987; Packer et al 1989; Meredith 1994). Hemorrhage occurs within the ﬁrst few days after surgery but may occur months or years later. Two thirds of all hemorrhages occur during the ﬁrst 6 months (Tolentino et al 1989). Various medications and surgical techniques have been utilized to prevent vitreous hemorrhage. Several interventions has been reported to be successful in preventing hemorrhage in the ﬁrst few days after surgery, but the percentage of cases with signiﬁcant hemorrhage 2–4 weeks after surgery has not been changed by any of these approaches. Such interventions included intrave- nous aminocaproic acid (de Bustros et al 1985a), layering of sodium hyaluronate on areas of severed ﬁbrovascular prolif- eration (Packer et al 1989), intraocular injection of thrombin (de Bustros et al 1985b), and endolaser photocoagulation (Liggett et al 1987). Air-ﬂuid exchange has not been shown to have long term beneﬁcial effect (Liggett et al 1987). Bevacizumab (Avastin, Genentech Inc., San Francisco, CA), a full length humanized monoclonal antibody to vascular endothelial growth factor (VEGF) was approved by the US Food and Drug Administration (FDA) for the treatment for metastatic colorectal cancer (Manzano et al 2006). Recent reports on the intravitreal injection of Avastin (IVA) showed promise for targeting VEGF-implicated intraocular neovascularization seen in age-related macular degeneration (Avery et al 2006) and proliferative diabetic retinopathy (PDR) (Spaide and Fisher 2006). It has been recently shown to enhance the clearance of vitreous hemorrhage and induce involution of retinal neovascularization, (Avery 2006; Spaide and Fisher 2006; Chen and Park 2006) and anterior segment neovascularization (Avery 2006; Davidorf et al 2006; Oshima et al 2006; Grisanti et al 2006) with no reported complications. This prospective comparative randomized study was constructed to study the effect of preoperative intravitreal injection of bevacizumab on the procedure of diabetic vit- rectomy and on its postoperative course. Methods Thirty patients with PDR undergoing pars plana vitrectomy (PPV) were randomized by diagnosis into 2 groups; group 1 undergoing PPV (15 patients) and group 2 undergoing PPV with preoperative IVA (15 patients) (Table 1). Cases of both groups were matched as possible according to sur- gical indication and preoperative visual acuity. In group 2, bevacizumab was injected 5 to 7 days prior to surgery. The admission criteria were TRD involving or threatening the macula, TRD plus vitreous hemorrhage, nonclearing vitreous hemorrhage of at least one month and massive pre-retinal subhyaloid bleeding covering the posterior pole. Full preop- erative and postoperative evaluation included best-corrected visual acuity (VA), fundus biomicroscopy, gonioscopy, and ultrasonography if the fundus could not be seen. All the patients were examined postoperatively at 1, 7 days, 2 weeks, 1 month, and thereafter monthly up to the end of follow-up. The main outcome measures were feasibility of surgery and postoperative complications. Feasibility of surgery was evaluated through recording the time of surgery, frequency of intraoperative bleeding, frequency of use of endodiathermy, relaxing retinotomies, use of perﬂuorocarbon liquid (PFCL), and use of silicone oil tamponade. The time of surgery was calculated as the time from the entry of the probes in the vitreous cavity till the closure of the vitrectomy ports. This time was calculated by revision of the video recordings of surgeries. Additional procedures as elective phaco-surgery Age, y, mean (SD)/(range) Indication of surgery, n (%) TRD TRD + vitreous Hge. Preretinal Hge. Dense vitreous Hge. Follow-up, mo., mean (SD)/(range) Table 1 Age, follow-up, and distribution of cases according to surgical diagnosis Group 1 Group 2 PPV Avastin + PPV 46 (12)/(24–65) 44 (11)/(23–57) 4 (26.7) 6 (40) 2 (13.3) 3 (20) 11.7 (3.0)/(7–17) 4 (26.7) 8 (53.3) 1 (6.7) 2 (13.3) 12.9 (3.2)/(7–18) P value (w) 0.7265 0.2869 P value (chi) 1 0.7152 1 1 Abbreviations: SD, standard deviation;TRD, tractional retinal detachment; Hge, hemorrhage;Y, years; mo, months; PPV, pars plana vitrectomy; w,Wilcoxon two-sample test; chi, chi square test. 710 Clinical Ophthalmology 2008:2(4)