The central retinal vein (retinal vein) is a short vein that runs through the optic nerve, leaves the optic nerve 10 mm from the eyeball and drains blood from the capillaries of the retina into either superior ophthalmic vein or into the cavernous sinus directly.Your retina is a thin layer of tissue that lines the back of your eyeball. It turns light into signals to the brain which interprets them as sight. When a vein in the retina becomes blocked, it’s called retinal vein occlusion. This can give you blurry vision or even sudden permanent blindness in that eye It's similar to retinal artery occlusion, which is sometimes called an eye stroke.