When one of the vessels that carry blood to your eye’s retina gets blocked, it can cause you to lose your eyesight. This problem often happens suddenly and without any pain. This is called a central retinal artery occlusion (CRAO). 

Your retina is the layer of nerve tissue at the back of your inner eye that senses light. Like a tiny video camera, your retina turns images into electrical signals. Your optic nerve carries these signals to your brain. If a blockage of a blood vessel happens in your retina, it can be very serious. The blockage usually comes from a blood clot or cholesterol deposit in your blood vessel. This is a serious condition. You should seek prompt medical attention. If a blood clot breaks free and moves to the brain, it could cause a stroke. The signs of CRAO are easy to spot. They are:

Sudden blindness in one of your eyes
Sudden, complete blurring of eyesight in one eye
Steady loss of eyesight in one eye over a few weeks

The symptoms may last a few seconds or minutes. Or, they might be permanent. If you have only partial blurring or loss of eyesight, you likely have branch retinal artery occlusion.