Branch Retinal Vein Occlusion
SALIENT FEATURES
Branch retinal vein occlusion (BRVO) is a venous occlusion at any branch of the central retinal vein. It is thought to be secondary to venous compression or narrowing.
Other possible causes include vascular degenerative changes and hypercoagulable states. Risk factors include hypertension and hyperlipidemia.2
Occurring more commonly than central retinal vein occlusion (CRVO), the prevalence of BRVO is 4.42 per 1000 people, with an estimated 13.9 million persons affected worldwide.1
The diagnosis of BRVO is clinical, relying on fundoscopic evaluation for hemorrhages, cotton wool spots, exudates, edema, and tortuous veins along the distribution of the occluded vein.3 Chronic changes include vessel sclerosis and collateral formation.
Complications include macular edema, ischemic maculopathy, retinal neovascularization, and vitreous hemorrhage. Macular edema is the most common of these complications leading to reduced visual acuity.2
OCT IMAGING
OCT is helpful in diagnosis and monitoring therapeutic responses of macular-involving BRVO-associated edema. The classic morphologic features of edema include intraretinal fluid which appears as hyporeflective cystic spaces within the retina (Figure 9.1). Subretinal fluid
may also be present as a hyporeflective space between the retina and RPE. Volumetric analysis demonstrates edema respecting the horizontal raphe.
FIGURE 9.1 A, Optical coherence tomography (OCT) of a patient with branch retinal vein occlusion (BRVO)-associated macular edema highlighting hyporeflective cystoid spaces (white asterisk), hyperreflective foci (green arrows) within the retina, as well as hyperreflective material within the cystic spaces (red arrows). Close examination demonstrates disorganization of the retinal inner layer (DRIL) (yellow arrow). B, OCT volumetric data displayed on a near-infrared imaging of the macula in a patient with superior BRVO demonstrate superonasal retinal thickening respecting the median raphe.
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