Evaluation of Macugen Treatment of Macular Edema Due to Branch Retinal Vein Occlusion

Retinal venous occlusive disease, which includes central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO), is second only to diabetic retinopathy as a cause of vision loss due to retinal disease. The main cause of vision loss in all of these disorders is the development of macular edema. Current clinical practice based on randomized controlled clinical trials (ETDRS, BVOS) employs laser photocoagulation, either in a focal or grid pattern, to treat macular edema associated with diabetic retinopathy and branch retinal vein occlusion. Unfortunately, laser photocoagulation is ineffective in central retinal vein occlusion (CRVO), and no proven therapy exists for CRVO. The pathogenesis of macular edema in retinal vascular diseases is generally accepted to be increased levels of vascular endothelial growth factor (VEGF) due to ischemic or other stimuli. VEGF is known to be one of the most potent stimulators of vascular leakage in humans. Therefore, it seems sensible to study inhibition of VEGF to reduce vascular leakage, reduce macular edema, and improve vision in these retinal vascular disorders. Phase 2 randomized, controlled clinical trials of Macugen in diabetic macular edema and in macular edema associated with CRVO have been conducted. In the diabetes trial, patients treated with Macugen had improved vision, reduced macular edema as measured by optical coherence tomography (OCT), and reduced need for laser treatment compared to patients treated with sham injections. In the CRVO trial, patients treated with Macugen 1 mg every 6 weeks for 24 weeks had improved vision and reduced macular edema at week 30 compared to sham. This is the first randomized trial of treatment for CRVO to show a benefit over control. Based on these positive findings, we plan to study Macugen treatment of macular edema due to BRVO.