Sites for Retinal Vein Occlusions

Retinal vein occlusions can be classified by site of occlusion as shown in this diagram. Ninety-five percent of branch retinal vein occlusions occur at arteriovenous crossings. Branch retinal vein occlusions that occur within the optic cup can be difficult to distinguish from a hemicentral retinal vein occlusion. Central retinal vein occlusions and hemicentral retinal vein occlusions are optic nerve-sited retinal vein occlusions. This classification of retinal vein occlusions was devised by Beaumont and Kang (Beaumont PE, Kang HK. Clinical characteristics of retinal venous occlusions occuring at different sites. Br J Ophthalmol. 2002;86: 572-580).