Amaurosis fugax is a temporary episode of decreased vision, usually lasting no more than 10 to 15 minutes, that is sometimes described as "closing a curtain" on one eye.Īlthough retinal vein occlusion also causes painless loss of vision, this vision loss sometimes develops gradually over several days or weeks rather than suddenly. In about 10% of those affected, this loss of vision is preceded by one or more episodes of a condition called amaurosis fugax. The usual symptom of retinal artery occlusion is a sudden, painless, persistent, substantial loss of vision in one eye. Or it can develop as part of another disease, such as systemic lupus and some cancers. Hypercoagulable states are conditions that cause people to have a higher than average risk of forming blood clots. Risk factors for this form of retinal vessel occlusion include older age, high blood pressure, diabetes, smoking, glaucoma, and hypercoagulable states. This can cause minimal or substantial loss of vision, depending on the extent of this retinal damage. When the vein is blocked, blood flow backs up and causes tiny hemorrhages, areas of swelling, and other pressure-related damage in portions of the retina that are located near the blocked blood vessels. The retinal vein carries blood away from the retina. In diabetic retinopathy, the blood vessels affected are much smaller than the arteries involved in classic retinal artery occlusion. Diabetic retinopathy (which is a common condition) can be thought of as an occlusive condition of the retinal blood vessels. In almost all cases, only one eye is affected. People more likely to be affected are older and have a history of heart disease, high blood pressure or diabetes. Overall, retinal artery occlusion is an uncommon problem. Less often, a retinal artery occlusion may be caused by vasculitis (inflammation of the artery's wall), trauma, sickle cell disease, clotting disorders, oral contraceptives or damage from radiation treatments. Rarely, pieces of a tumor from elsewhere in the body can embolize. For this reason, the embolus is often interpreted as a warning sign of cardiovascular disease elsewhere, especially in the carotid artery. An embolus (floating blood clot or debris in the bloodstream) – In the retinal artery, an embolus is usually a tiny blood clot or a piece of atherosclerotic plaque that has been carried through the bloodstream from the heart, aorta or carotid artery (in the neck).Atherosclerosis is a common cardiovascular problem that produces cholesterol deposits called plaques along the walls of arteries, decreasing blood flow. A thrombus (blood clot) – Inside the retinal artery, a blood clot typically develops at a site where the artery's lining has already been damaged by a chronic condition, such as high blood pressure (hypertension), diabetes or atherosclerosis.In adults, there are two main reasons that the retina's artery would become blocked: a thrombus or an embolus. This can cause permanent and often substantial loss of vision. Unless normal circulation to the retina can be restored promptly, these cells will die within a few minutes or hours depending on how completely the blood flow is obstructed. When a blockage occurs in the retina's main artery, or in one of its small branches, the retina's light-sensitive cells gradually begin to suffocate from lack of oxygen. The retinal artery carries oxygen-rich blood to the retina. If blockage occurs in a smaller branch vessel, there may be partial vision loss or no symptoms. If a main vessel becomes occluded, the eye typically loses vision, often suddenly. If either blood vessel or one of their smaller branches is blocked, blood circulation to the retina can be significantly disrupted. Blood circulation to most of the retina's surface is primarily through one artery and one vein. The retina is the light-sensitive layer at the back of the eye that is responsible for vision.
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