Retinal Vein Occlusions.

Abstract

Retinal vein occlusions (RVOs) have been defined as retinal vascular disorders characterized by dilatation of retinal veins with retinal and subretinal hemorrhages, macular edema, and a varying degree of retinal ischemia. Retinal angiography, either as fluorescein and indocyanine green (ICG) angiography or in the form of optical coherence tomography (OCT)-based angiography, is essential for the diagnosis and assessment of the prognosis of RVOs. It allows the differentiation of diverse types of RVOs, such as perfused or nonperfused, as well as the detection of different modalities in the natural history of RVOs. OCT angiographic imaging in combination with dye angiography (fluorescein or ICG) is the most effective method to assess the amount and location of cystoid macular edema and the persistence, regression, and degree of ischemia. OCT can additionally display the presence and integrity of the outer limiting membrane and of the inner and outer segments of the photoreceptors as useful biomarkers for the prognosis and as a guide for the treatment of RVO. Due to the relatively often benign and self-limiting course of nonischemic RVOs, therapy may initially be delayed. If macular edema extends into the foveolar region and persists, intravitreal medical therapy including steroids (triamcinolone; fluocinolone or dexamethasone in slow-release devices) and/or anti-VEGF (vascular endothelial growth factor) drugs (bevacizumab, ranibizumab, aflibercept) may be intravitreally administered, avoiding the irreversibly destructive effect of laser coagulation, which previously was applied in a 'grid' pattern over the extrafoveolar leaking area. The side effects of intraocularly applied steroids in relatively young patients including cataract formation and ocular hypertension have to be considered.