What is retinal vein occlusion and what causes it?
Retinal vein occlusion is when one of the tiny retinal veins becomes blocked by a blood clot. This means that blood cannot drain away from the retina as easily and there is a backlog of blood in the blood vessels of the retina. This can lead to a build-up of pressure in the blood vessels. As a result, fluid and blood start to leak from the blood vessels, which can damage and cause swelling of the retina, affecting your eyesight. There are two main types of retinal vein occlusion: • Branch retinal vein occlusion – the blockage occurs somewhere along the course of one of the four retinal veins. (One retinal vein drains each quarter of the eye.) • Central retinal vein occlusion – the blockage occurs in the main vein formed by the four retinal veins coming together. Branch retinal vein occlusion is two to three times more common than central retinal vein occlusion.
