This blockage is typically caused by a tiny embolus (clot) in the blood stream. The occlusion decreases the oxygen supply to the area of the retina nourished by the affected artery, causing permanent vision loss.

The lack of oxygen delivery to the retina may result in severe loss of vision.

Retinal artery occlusion is usually associated with sudden painless loss of vision in one eye. The area of the retina affected by the blocked vessels determines the area and extent of visual loss.

The main artery supplying blood to the eye is the ophthalmic artery; when it is blocked, it produces the most damage. A blockage in the main artery in the retina is called central retinal artery occlusion (CRAO), which often results in severe loss of vision.