Retinal Vein Occlusions

Retinal vein occlusions (RVOs) are second to diabetic retinopathy in the prevalence as retinal vascular disorder and are characterized by dilatation of the retinal veins with retinal and subretinal hemorrhages, macular edema, hard retinal exudates, retinal ischemia, and consequent atrophy of the retina and optic nerve. They are differentiated into central RVOs and branch RVOs (BRVO), into ischemic versus nonischemic RVOs, and in the case of BRVOs, into intrapapillary BRVOs and extrapapillary BRVOs. Diagnosis is based on ophthalmoscopy, fluorescein angiography, and spectral-domain optical coherence tomography. The latter can display the presence and integrity of the retinal outer limiting membrane and of the inner and outer segments of the photoreceptors as useful information for prognosis and a guide for treatment. Risk factors for RVOs are glaucoma and arterial hypertension. Ischemic RVOs can develop iris neovascularization and secondary angle-closure glaucoma. Formerly, therapy consisted of laser photocoagulation in a "grid" pattern over the leaking area, leading to a reduction of macular edema and, as adverse effect, to focal retinal destruction. Intravitreal medical therapy including steroids and vascular endothelial growth factor inhibitors shows a marked antiedematous effect leading to an at least temporary reduction in foveal edema and correspondingly improves visual function. Intravitreal medical therapy is associated with the disadvantage of a limited duration of its effect and the advantage of not damaging the retina. A preventive therapy to avoid a recurrence of RVO or the development of an RVO in the contralateral eye has not been proven yet.