Intravitreal Avastin Versus Intravitreal Avastin and Triamcinolone in Central Retinal Vein Occlusion(CRVO)

Central retinal vein occlusion (CRVO) is a common retinal vascular disorder with potentially complications like reduced vision resulting from extensive intraretinal hemorrhage, retinal ischemia and persistent macular edema and neovascular glaucoma secondary to iris neovascularization. Macular edema is a common cause of severe visual loss in both branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO). Natural history data indicate that CRVO patients presenting with poor visual acuity (_20/200) have an 80% chance of being left with visual acuity less than 20/200 at final visit, whether the CRVO is ischemic or nonischemic at presentation. Treatments that target the secondary effects of venous occlusion, such as grid laser photocoagulation for macular edema and prophylactic panretinal laser photocoagulation for nonperfused CRVO, were shown to be ineffective in improving visual acuity in the Central Vein Occlusion Study (CVOS). Although panretinal photocoagulation is advocated for reducing the risk of neovascular glaucoma in patients with ischemic CRVO, recent clinical trials have failed to demonstrate any significant benefit with laser photocoagulation in the treatment of macular edema due to CRVO. A number of other treatment options are sometimes used in cases of CRVO, such as oral corticosteroids, intravitreal steroids, vitrectomy, hemodilution, intravitreal tissue plasminogen activator, hyperbaric oxygen, and laser or surgical chorioretinal anastomosis. Studies demonstrating the effectiveness of these treatments are inconclusive, although some benefits have been suggested in recent reports. In recent studies the benefit of antiVEGF agents in improving the macular edema due to CRVO have been shown. In this study we are going to compare the effect of intravitreal antiVEGF (Avastin) with combination of Avastin and Triamcinolon in improving the visual acuity and macular thickness in patients with recent (Less than 6 months) CRVO.