Nonresponsiveness, Resistance to the Treatment, Drug Switch And Combined Treatments in Macular Edema Secondary To Central Retinal Vein Obstruction

Retinal vein occlusion (RVO) is the second most common retinal vascular disease following diabetic retinopathy. Visual loss in central retinal vein occlusion (CRVO) may occur due to retinal ischemia, macular ischemia, macular edema or neovascular complications. In CRVO, macular edema can develop due to increased vascular permeability due to inflammation and elevated VEGF levels, and breakdown of the blood-retina barrier. In cases with CRVO, resistance and/or nonresponsiveness to the treatment develops in about one of three of the cases. The presence of relative afferent pupillary defect, vitreoretinal traction, poor macular and peripheral retinal perfusion, high blood urea and creatinine levels, ineffectiveness to other cytokines and factors, delay in the initiation of the treatment, VEGF receptor up-regulation, advanced age are risk factors for non-responsiveness. Positive results on visual acuity, central macular thickness and number of injections can be obtained by replacing one AntiVEGF agent with another and/or by combined treatments with steroids in treatment of the resistant/non-responsive cases.