Snapshot A 65-year-old man presents to the emergency department for progressive visual loss. He denies any photopsia or ocular pain. Medical history is significant for polycythemia vera. Physical examination is notable for engorged retinal veins with small retinal hemorrhages. Summary Occlusion of the retinal vein leading to retinal ischemia 3 types central retinal vein occlusion thrombus in the central retinal vein leading to involvement of the entire retina branch retinal vein occlusion occlusion in the distal retinal vein leading to involvement in the distal retina hemiretinal vein occlusion thrombus in either the superior or inferior hemiretina leading to involvement of half the retina Epidemiology Risk factors age hypertension diabetes smoking obesity hypercoagulability glaucoma retinal arteriolar abnormalities Pathophysiology Occlusion of the retinal vein leads to retinal ischemia the ischemia can result in neovascularization, resulting in complications such as glaucoma vitreous hemorrhage macular edema retinal detachment secondary to retinal traction Presentation Symptoms painless vision loss aymptomatic in certain cases of branch retinal vein occlusion Physical exam retinal edema retinal vein dilation retinal hemorrhage neovascular glaucoma chronic ischemia leads to neovascularization, which can encroach to the anterior chamber angle can cause pain eye due to increased intraocular pressure relative afferent pupillary defect severe cases Studies Fluorescein angiography indication confirms the diagnosis determines the degree of retinal nonperfusion Optical coherence tomography indication to quantify retinal thickening from fluid within the retina secondary to macular edema Differential Retinal artery occlusion differentiating factor pallor of optic disk and cherry red macula Treatment Medical observation indication brach or central retinal vein occlusion without macular edema or neovascularization intravitreal anti-vascular endothelial growth factor (VEGF) indication first-line for macular edema secondary to retinal vein occlusion intravitreal glucocorticoids indication second-line treated for macular edema secondary to retinal vein occlusion Surgical retinal laser photocoagulation indication first-line for neovascularization secondary to retinal vein occlusion Complications Neovascular glaucoma Vitreous hemorrhage Retinal traction Macular edema Prognosis Branch retinal vein occlusion typically has a better visual prognosis than central retinal vein occlusion