Hypercoagulability can be defined as the tendency to have thrombosis as a result of certain inherited and or acquired defects. Hypercoagulability is common etiology for CRVO as a venous thrombosis in the eye can occlude outflow of blood.
Hypertension is most often associated with atherosclerosis. Nearby arterial atherosclerosis is the most common cause of occlusion of the central retinal vein.
Diabetes mellitus is a metabolic disorder characterized either by insulin deficiency or resistance which causes hyperglycemia.
Retinal vein occlusion can be either non-ischemic or ischemic. Non-ischemic CRVO is a subacute process where blood supply to the retina is not compromised.
In non-ischemic CRVO, vision loss is mild to moderate, but not severe or total.
A few scattered dot-blot and flame hemorrhages may be seen in non-ischemic CRVO. Venous occlusion causes metabolic waste products to accumulate causing increased back-pressure to capillaries and then extravasation.
Retinal vein occlusion can be either non-ischemic or ischemic. Ischemic CRVO carries the poorer prognosis and involves a drastically reduced blood supply to the retina.
The vision loss in ischemic CRVO is often sudden, severe, and painless. Near-total blindness may occur.
On fundoscopy, the retina may be described as having a "blood and thunder" appearance from all the dot-blot and flame hemorrhages across the retina.
Cotton wool spots may also be evident. They are fluffy, white patches on the retina due to axoplasmic stasis.
Papilledema is a critical finding, which indicates increased intra-ocular pressures.
The management depends on the type of CRVO. Observation is best for non-ischemic CRVO, but the underlying cause (e.g. hypertension, hypercoagulability, diabetes) must be addressed and treated.
Panretinal laser photocoagulation can be used to treat ischemic CRVO. This procedure involves the use of a laser to burn retinal tissue in an effort to avoid neovascularization from ischemia.
VEGF inhibitors like ranibizumab and bevacizumab can be administered as an intra-vitreal injection for ischemic CRVO. These also inhibit neovascularization.
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