It has been demonstrated that intravitreal steroid, such as dexamethasone or triamcinolone in eyes with macular edema due to retinal vein occlusion or diabetic retinopathy, causes a reduction of arteriolar or venular vessel diameter probably due to a blockage of vascular endothelial growth factor with macular edema improvement [16,17]. The gene discussed is VEGFA; the disease is macular retinal edema.