The retina—the layer of light-sensitive cells at the back of the eye—is nourished by blood flow, which provides nutrients and oxygen that nerve cells need. When there is a blockage in the veins into the retina, retinal vein occlusion may occur.
Central retinal vein occlusion (CRVO) is a blockage of the main vein in the retina. (Blockage of the small veins in the retina is called branch retinal vein occlusion, or BRVO.) The blockage causes the walls of the vein to leak blood and excess fluid into the retina. When this fluid collects in the macula (the area of the retina responsible for central vision), vision becomes blurry.
There are two types of CRVO:
- Non-ischemic CRVO. This is a less serious form of CRVO, which accounts for a majority of cases.
- Ischemic CRVO. This is a more serious form of CRVO that can lead to the development of significant complication, vision loss and possibly loss of eye.