Retinal vein occlusions (RVO) are categorized into branch (BRVO), hemiretinal (HRVO) or central retinal vein occlusion (CRVO) depending on the location of the occlusion. The condition can further be categorized by the presence or absence of macular edema and if the condition is ischemic or nonischemic.
Vision loss from retinal vein occlusions is secondary to macular edema and if ischemic, has the risk to develop neovascularization and neovascular glaucoma. OCT can assist in detecting macular edema secondary to retinal vein occlusions and track response to treatment. Macular edema in retinal vein occlusions causes diffuse leakage, especially in CRVO. The macular edema is driven by ischemia and release of vascular endothelial growth factors (VEGF) that increases the inner retinal blood-brain barrier causing leakage of intraretinal fluid.
Macular edema secondary to branch retinal vein occlusion will respond to argon grid laser and anti-VEGF therapies (Lucentis, Eylea, avastin).
Macular edema secondary to central retinal vein occlusion will respond to anti-VEGF therapies (Lucentis, Eyelea, and avastin) and intravitreal dexamethasone implant (Ozurdex).
Figure 1: Hemiretinal vein occlusion (HRVO) with macular edema. There are intraretinal cysts and edema causing elevation temporal to the fovea.
Figure 2: Branch retinal vein occlusion with macular edema but not involving the fovea. SD-OCT vertical line scan reveals intraretinal edema superior to the fovea with intact EPIS and COST lines over the fovea.
Suggest readings:
BRAVO- http://www.ncbi.nlm.nih.gov/pubmed/21684606
CRUISE- http://www.ncbi.nlm.nih.gov/pubmed/21715011
HORIZON trial- http://www.ncbi.nlm.nih.gov/pubmed/22301066
The Branch Vein Occlusion Study: Argon laser photocoagulation for macular edema in branch vein occlusion.- http://www.ncbi.nlm.nih.gov/pubmed/6383055
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