The use of anti-angiogenic drugs for central retinal vein occlusion

Central retinal vein occlusion (CRVO) is one of the common causes of visual loss. The main reasons for decreased vision are development of macular edema, macular ischemia and neovascular glaucoma. The introduction of anti-vascular endothelial growth factor (VEGF) drugs for CRVO in 2005 demonstrated marked improvement in visual acuity, macular edema and ocular neovascularization. However, the absence of clear guidelines for the treatment of CRVO presents a genuine therapeutic challenge. In a national study conducted among the Israeli society of retinal specialists (personal communication), it was found that most of these specialists would recommend intravitreal anti-VEGF drug injection immediately upon the diagnosis of macular edema in non-ischemic CRVO with visual acuity of 6/15 or less. Only 21% would recommend this treatment in ischemic CRVO with visual acuity of 6/60 or less, if no macular edema exists. After the edema resolves, 94% would follow-up the patients by imaging with optical coherent tomography every 4-6 weeks, and recommend further treatment accordingly. Large prospective controlled studies are warranted in order to address the important issues of when to start anti-VEGF treatment for CRVO, when to withhold treatment, and recommended treatment intervals.