There are four types of retinal vascular occlusions (RVO). All have similar symptoms of acute (sudden) and painless loss of vision.
In general, vein obstructions occur when the vessel is compressed from the outside of the blood vessel whereas artery obstructions occur when cholesterol plaque (or other substances) travel through the blood stream and become lodged in a blood vessel.
Vein and artery occlusions have characteristic appearances and can be easily diagnosed by a retina specialist.
Artery occlusions are more likely to be associated with coronary artery disease and stroke.
The four types of retinal vascular occlusions include:
- Branch retinal vein occlusion (BRVO)
- Central retinal vein occlusion (CRVO)
- Branch retinal artery occlusion (BRAO)
- Central retinal artery occlusion (CRAO)
Branch Retinal Vein Occlusion
Compared to a central vein occlusion, this is a “partial” occlusion of the retinal vein. Usually branch occlusions involve about 50% or less of the retina. If the macula becomes involved, there is usually moderate vision loss. On occasion, the macula is not involved and vision remains normal.
Treatment of BRVO includes laser surgery, injections of anti-VEGF and/or intraocular steroids including Ozurdex, a sustained release device which allows continuous treatment for up to 4-6 months.
Central Retinal Vein Occlusion
The entire retinal vein is occluded. Severe vision loss is normally experienced. Unlike the branch vein occlusion, the macula is always involved.
Treatment of CRVO may include laser, anti-VEGF injections or sustained release steroids. Vision usually does not improve as well as the branch retinal vein occlusion.
Branch Retinal Artery Occlusions
Branch artery occlusions do not involve the entire retina and, similar to venous occlusions, less than 50% of the retina is involved. If the macular area is involved, central vision is decreased.
Branch artery occlusions do cause retinal edema, but the vision loss is usually more permanent though there is resolution of the retinal swelling.
Both branch and central artery occlusions are caused by an embolus: usually a cholesterol plaque carried through the bloodstream and becomes lodged in a retinal artery.
Central Retinal Artery Occlusion
As with the branch artery occlusion, an embolus lodges in the central artery thus cutting off blood flow to the entire retina. Vision loss is severe and usually does not respond well to treatment.
Historically, many different methods have been described to dislodge the embolus, but none with resounding success.
Patients with artery occlusions should be assessed for the risk of cardiovascular disease and stroke. It’s important that your retina specialist or eye doctor coordinate care with your primary care physician.
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