Arteries bring blood into the eyes while the veins take the blood out of the eyes back towards the heart. Sometimes a retinal vein can become occluded, and the blood gets backed up like a clogged drain. When this occurs, the blood ends up spilling into the retina, causing retinal bleeding and often retinal swelling (edema). The area of the retina affected by the blocked vein is not able to get the necessary nutrients and can often become ischemic. In severe cases, the retina in the affected area may die.
There are two main types of vein occlusions. A central retinal vein occlusion occurs when the single main vein that drains the retina becomes blocked. A branch vein occlusion occurs when a smaller branch off the main single main vein becomes blocked. Depending on how bad the occlusion is, both the central and branch vein occlusions can lead to severe ischemia and swelling of the retina. In these situations, the patient may experience painless loss of vision.
Your eye doctor will be able to diagnose this condition with a careful dilated examination. Additional testing with fluorescein angiograms and OCT are often obtained to assess the degree of damage to the retina.
Branch retinal vein occlusions can sometimes be helped with focal or grid macular laser treatment if macular edema has developed. Macular edema from central vein occlusions generally does not respond to laser. There is currently growing interest in using injectable steroids or other medicines to help with the macular swelling in both branch and central vein occlusions. Patients with vein occlusions need to be monitored on a regular basis for the development of abnormal blood vessels that the eye sometimes develops in its attempt to resupply the damaged retina. If these abnormal blood vessels are found, your doctor will recommend a different laser treatment (panretinal photocoagulation) to get rid of these abnormal blood vessels.
Central Retinal Vein Occlusion (CRVO)
Branch Retinal Vein Occlusion (BRVO)