What does blood in the back of the eye signify, anyway? It could be a retinal vein occlusion, an ocular disorder that can occur in older people when the blood vessels to the retina are blocked. The retina is the back part of the eye where light focuses and transmits images to the brain. Blockage of the veins in the retina can cause sudden vision loss. The severity of vision loss depends on where the blockage is located. Blockage at smaller branches in the retinal vein is referred to as branch retinal vein occlusion (BRVO).  Vision loss in BRVO is usually less severe, and som...