Retinal vein occlusion is a common form of retinal vascular disease, especially in middle-aged and older individuals. It occurs when the vein providing outflow of blood from vasculature in the eye becomes blocked.

The retina is nourished and cleansed by a set of tiny blood vessels, the retinal arteries and the retinal veins. Especially in older persons, these fine vessels sometimes become blocked (occluded) with a blood clot (thrombosis) or fatty deposit (embolus).

The symptoms depend on what...