Retinal Vessel Occlusion
What Is It?
The retina is the light-sensitive layer at the back of the eye that is responsible for vision. Blood circulation to most of the retina's surface is through only one artery and only one vein. If either blood vessel or one of their smaller branches is blocked, blood circulation to the retina can be significantly disrupted. The blockage is called an occlusion. When this happens, the eye typically loses vision, often suddenly. The condition is painless.
Retinal Artery Occlusion
The retinal artery carries oxygen-rich blood to the retina. When a blockage occurs in the retina's main artery, or in one of its small branches, the retina's light-sensitive cells gradually begin to suffocate from lack of oxygen. Unless normal circulation to the retina can be restored promptly, these cells will die within a few minutes or hours depending on how completely the blood flow is obstructed. This can cause permanent and often substantial loss of vision.
In adults, there are two main reasons that the retina's artery would become blocked: a thrombus or an embolus.