Venous occlusion

Occlusion /oc·clu·sion/ 1. obstruction. 2. the trapping of a liquid or gas within cavities in a solid or on its surface. 3. [more]Venous occlusion - Community and Resources

sometimes, the main vein that drains blood from the eye can become blocked. This is called central retinal vein occlusion. It causes blood and fluid to back up into the retina.
For more information, See Eye Diseases on the MD Support web site.