El-Batarny vitrectomy making surgery easier. In the current study, there was marked reduction of intraoperative bleeding in group 2 which was reﬂected in minimal need to use the endodia- thermy. The nearly absence of intraoperative bleeding in Avastin-treated cases can explain the easier dissection of membranes in that group. It is sometimes very difﬁcult to peel clotted blood tightly adherent to the retinal surface which had led to the higher incidence of retinal iatrogenic breaks in group 1. Lee and Abrams (2001) reported that the removal of hemorrhage not only may extend a preexisting retinal break, but also may create new retinal breaks; therefore hemorrhage should be avoided whenever possible. The absence of intra- operative bleeding with evident involution of neovascular complex explains the higher incidence of using gas and air in group 2 in contrast to higher incidence of silicone oil in group 1. Approximately 60% of eyes develop recurrent vitreous hemorrhage some time in the postoperative period. Hemorrhage is usually within the ﬁrst few days after surgery (Liggett et al 1987; Tolentino et al 1989). Two thirds of all hemorrhages occur within the ﬁrst 6 months (Tolentino et al 1989; Lee and Abrams 2001). Novak and colleagues (1984) reported that vitreous hemorrhage was present on the ﬁrst postoperative day in (63%) of eyes. This early hemorrhage cleared in an average of 9.1 weeks in phakic eyes and 3.4 weeks in aphakic eyes. In the early postoperative period, the sources of hemor- rhage are often difﬁcult to determine. However, most of the surgeons believe that severed ﬁbrovascular membranes are the usual source of bleeding which usually occurs within 1 week of surgery (Meredith 1995; Lee and Abrams 2001). In the Avastin-treated cases, no postoperative bleeding was reported in all cases. A single dose of bevacizumab was found to provide complete VEGF blockade for a minimum of 4 weeks (Beer et al 2006), thus providing a haemostatic effect extending beyond the absorption of the gas. This might have prevented recurrence of bleeding in the early postoperative period in group 2 giving a chance for full PRP and cryo- therapy to induce persistent neovascular regression. In group 1, on the other side, 3 cases out of 6 cases treated with gas tamponade, (50%), developed early postoperative bleeding while in the remaining 9 cases, the long-term silicone tam- ponade was the main factor in preventing bleeding in the early postoperative period. The time of surgery was signiﬁcantly reduced in the avastin group compared to group 1. In a study done by Rizzo and colleagues (2007), the mean surgical time was reduced from 83 minutes to 57 minutes after preopera- tive injection of Avastin as well as reduction of frequency of intraoperative bleeding and use of endodiathermy. Good 714 visualization due to absence of signiﬁcant intraoperative bleeding and easier dissection seem to be the reasons for the reduction in the surgical time. Scholda and colleagues (2007), reported an extensive obliteration of neovascularization with only little intraoperative bleeding during surgery after intravitreal Avastin. Chen and Park (2006), after injecting avastin in a case of TRD 1 week before surgery, reported that most epicenters of neovascularization peeled with blunt dissection, suggesting that the recently active neovascular complex had regressed and ﬁbrosed. In the Avastin-treated cases, no increase in the extent of tractional on the retina was observed. This is because of the short duration between intravitreal injection and surgery which did not exceed 1 week. Scholda and colleagues (2007) reported on 10 cases with advanced PDR treated with avastin 2–3 weeks prior to surgery, the authors reported marked contraction of the remaining ﬁbrous tissue. Arevalo and col- leagues (2008), reported that time from injection to progress or development of TRD had a mean of 13 days (range: 3 to 31 days). The authors reported development or progression of TRD in 11 out of 211 eyes (5.2%) after IVA. The anatomical and visual results seem comparative in both groups. Vision improved in 87% in group 2 and 80% in group 1 with 27% achieving VA of 20/50 or better in both groups. Improved vision after vitrectomy is now reported for 60%–80% of eyes with traction macular detachments man- aged with membrane dissection and PPV. Approximately 20% of patients achieve vision of at least 20/40 (Meredith 1994). In the Diabetic Retinopathy Vitrectomy Study, patients with active proliferation and good vision preop- eratively attained vision of 20/40 or better in 41% eyes postoperatively (DRVS 1988). In the current study, 5 cases (33%) in group 1 and 6 cases (40%) in group 2 had preopera- tive vision between 0.05 and 0.1. Thompson and colleagues (1986) reported poor initial visual acuity as a predictive factor of poor visual prognosis. Good anatomical results were achieved in both groups, however in group 2 this was achieved with short term endot- amponade (gas or air) in 80% of cases with less frequency of second surgery while in group 1, silicone oil use was 60% with subsequent higher rate of resurgery; silicone oil ± cataract surgery. The choice of silicone oil in this group was strongly related to bleeding tendency which was minimized in group 2 by the IVA. Riedel and colleagues (1990) rec- ommended that oil use be reserved for cases with advanced PDR or intractable PVR. Silicone oil provides the longest term tamponade, and has the additional beneﬁt of noncritical Clinical Ophthalmology 2008:2(4)