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Central Retinal Vein Occlusion (CRVO)

Retina with CRVO
Central Retinal Vein Occlusion (CRVO) can cause devastating sudden loss of vision. The central retinal vein which drains the used blood out of the retina becomes clogged. This causes a back flow of blood and serum which causes the blood to leak into the retina and cause swelling.

There are two types of CRVO: ischemic and non-ischemic. The "ischemia" refers to cases where the flow of blood has been compromised in the arterioles as well and thus parts of the retina are not receiving blood. The disctintion between ischemic and non-ischemic is based on findings on an angiogram. Eyes with ischemic CRVO usually have worse vision and are more likely to go on to having complications. The maincomplication is the growth of new abnormal blood vessels (neovascularization)which may clog the outflow path of eye fluids and cause high pressure. This high pressure may cause the eye to lose further vision and become painful. Patients with CRVO are typically followed monthly for the first few months to check for development of neovascularization. These new vessels are first noticed on the iris. Laser treatment is effective in causing the abnormal vessels to go away. However, vision is not improved with laser treatment. In fact, 80% of people with vision worse than 20/400 will retain vision at that level.

Several experimental methods for improving vision in patients with CRVO are currently being tested. These including injection of steroids (Kenalog) or TPA in the eye, Radial Optic Neurotomy (RON), and canulization of the central retinal vein.
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