Definition of Retinal vein occlusion:

Retinal vein occlusion is a blockage of the small veins that carry blood away from the retina. The retina is the layer of tissue at the back of the inner eye that converts light images to nerve signals and sends them to the brain.

Causes, incidence, and risk factors:

Retinal vein occlusion is most often caused by hardening of the arteries (atherosclerosis) and the formation of a blood clot.

Blockage of smaller veins (branch veins or BRVO) in the retina often occurs when retinal arteries that have been thickened or hardened by atherosclerosis cross over and place pressure on a retinal vein.

Rick factors for retinal vein occlusion include:

• Atherosclerosis
• Diabetes
• High blood pressure (hypertension)
• Other eye conditions, such as glaucoma, macular edema, or vitreous hemorrhage

Because the risk of these disorders increases with age, retinal vein occlusion most often affects older people.

Blockage of retinal veins may cause other eye problems, including:

• Glaucoma (high pressure in the arteries), caused by new, abnormal blood vessels growing in the front part of the eye
• Macular edema, caused by the leakage of fluid in the retina