The retina has its own blood supply. The central retinal artery enters the optic nerve and fans out over the retinal surface. The blood is then collected through the branch retinal artery, and exits through the central retinal vein, returning to the optic nerve.
Retinal vein occlusion (RVO) is a condition that occurs when the retinal vein (either central or branch) becomes blocked. This effects blood and oxygen supply exiting the eye and causes retinal oedema (or swelling).
Retinal vein occlusions can be partial, with relatively normal oxygen levels, or complete, with very low oxygen levels. Depending on whether the occlusion is partial or complete, vision can range from almost no disturbance to complete vision loss.
There are two types of retinal vein occlusion that can occur:
The main symptom of retinal vein occlusion is a sudden loss of vision. It usually only occurs in one eye.
Retinal vein occlusion is primarily a vascular disease most often occurring in relation to one or more of the following conditions:
Many patients will regain vision over time, even without treatment. However, it rarely returns to normal. The blockage cannot be removed, so treatment focuses on prevention of further blockages and on managing complications such as abnormal vessel growth, or macular oedema (swelling).
Sometimes laser can be performed to remove abnormal vessel growth in the eye. Your ophthalmologist will be able to determine whether or not laser treatment will help to improve your condition.
The outcome varies. People who experience retinal vein occlusion often regain useful vision over time.
Blockages cannot be removed once they have occurred, so prevention methods to stop a recurrence are the best way forward. These include medication for blood pressure and cholesterol, adoption of healthy lifestyle habits, and improved diabetes control. Having macular oedema or glaucoma is more likely to lead to a poor outcome.