context: Like a stroke in the brain, this happens when blood flow is blocked in the retina, a thin layer of tissue in the eye that helps you see. It can cause blurry vision and even blindness. Arteries carry blood to the retina from the heart. Without blood flow, the cells in the retina don't get enough oxygen. They can start to die within minutes or hours. An eye stroke is an emergency. If you don't get treated right away, you can damage your vision permanently. Usually, the blockage comes from a blood clot. The clot may form in the retina or travel there from another part of the body. The blockage also can happen after a piece of fatty plaque plugs the artery. If you have a condition that affects the blood vessels -- including diabetes, high blood pressure, high cholesterol, or heart disease -- it can raise your chances of an eye stroke. Other things that make a retinal artery occlusion more likely include: Being 40 or older Being a man Smoking Trauma to the eye Damage from radiation treatments Kidney disease Clotting disorders such as sickle cell disease Birth control pills Carotid artery disease Abnormal heart rhythms like atrial fibrillation Vasculitis, an inflammation of the blood vessel wall Pregnancy The main sign of eye stroke is a sudden change in sight. It almost always happens in only one eye. You usually won't feel any pain. You may notice: Loss of all or part of your sight Not able to see out of side of your eyes Blurry or distorted vision Blind spots The most common type of eye stroke is called central retinal artery occlusion. It can leave you with little useful vision. You might be able to see a hand move, but not much more. Rarely, your vision might return on its own. If you have the less serious blockage in the smaller arteries, your vision may go back to normal about 80% of the time. Your doctor will check your eyes and ask about your medical history. She may ask you to read an eye chart. She'll also put drops in your eyes to open up your pupils and use an ophthalmoscope to check your retina for any blockages or bleeding. You also might have other tests: Visual field test. You look into a machine and click a button each time you see a light. It checks if you lost any peripheral vision, which is what you see out the sides of your eyes. Slit-lamp. You sit in front of a special microscope. It shines a narrow line of light in your eye so your doctor can look for anything unusual. Fluorescein angiography. Your doctor injects a harmless dye in your arm. It moves through your bloodstream to your retina. A special camera takes pictures of your eye to show which blood vessels are blocked. Optical coherence tomography. You get drops to dilate your pupils. Then a machine scans your eyes to make a detailed image of the retina. If your doctor thinks a clot from another part of the body caused the blockage, she may suggest other tests to look for problems in your arteries and heart. She also may order blood tests to check for clotting disorders and your cholesterol levels. Minutes count in order to save your vision after an eye stroke. You may avoid lasting injury if doctors can clear the central artery blockage and restore blood flows within 90-100 minutes. But after 4 hours, the blockage could damage your vision for good. Your doctor may try one or more of the following treatments: Eye massage. Your doctor will massage your closed eyelid with a finger to dislodge the clot. Carbon dioxide-oxygen. You breathe in a mixture of carbon dioxide and oxygen to increase blood flow to the retina. It also widens the arteries. Paracentesis. A specialist uses a small needle to remove a few drops of fluid from the front of your eye. This reduces pressure, which may increase blood flow in the retina. Medications. You may get drugs to bust clots or to lower the pressure in your eyes. These include drugs used for glaucoma, like acetazolamide ( Diamox). You usually get an eye stroke because of another medical issue, such as high blood pressure or diabetes. So keep your cholesterol, blood pressure, and blood sugar levels in check. If you have diabetes, get your eyes checked every year.