Retinal Vein Occlusion
A retinal vein occlusion occurs when an artery supplying blood to the eye hardens or swells and presses on a nearby vein and blocks it, making it difficult for blood to leave the eye. The restricted circulation leads to high pressure in the eye, which can in turn cause swelling, bleeding, growth of abnormal blood vessels, and partial or total vision loss.
Vascular occlusions do not cause a change in physical appearance, and they can occur with no pain or noticeable loss of vision. For these reasons, it is important to have routine eye exams and also to check one's own vision by closing one eye at a time.