Central Retinal Artery Occlusion
The retina is an essential part of the eye that plays a critical role in vision. It is a thin layer of tissue that lines the back of the eye, just like wallpaper in a room. When light enters the eye, it first passes through the cornea and the lens before reaching the retina. The retina detects the light and generates electrical signals. These signals are then transmitted by the optic nerve to the brain, where they are interpreted as visual images. Anything that disturbs the retina can potentially cause harmful effects on vision.
The retina has an intricate blood vessel system. A tiny artery, called the central retinal artery, travels through the middle of the optic nerve and into the retina to supply it with blood. Just after the central retinal artery enters the retina, it begins to progressively branch into smaller arterioles and then microscopic capillaries, much like a tree trunk and its many branches. This microscopic arterial system connects to a parallel set of microscopic veins that progressively merge into larger veins, culminating in the central retinal vein which also exits the retina through the optic nerve. Some of the most common problems a retina specialist sees are related to abnormalities in the blood vessel system of the retina.
A central retinal artery occlusion (CRAO) is a blockage that deprives the retina of its blood supply. This usually occurs suddenly without warning and can cause severe and permanent loss of vision in the affected eye. The extent of vision loss depends on how severely the artery is blocked. Treatment options to restore vision are often ineffective because the loss of blood supply causes irreversible damage to the retina within minutes of onset.
The most common cause of a CRAO is an embolus which has traveled through the bloodstream and, by chance, entered into the retinal circulation. The occurrence of a CRAO suggests that the afflicted person may be at risk of other embolic events including stroke. Thus, a general medical evaluation by a primary care physician looking for potential embolic sources in the heart and major arteries is very important so that any such abnormalities can be properly treated. The goal of the evaluation is prevention of other events, not the return of vision. Another potential cause of CRAO is inflammation, and your physician may consider this as well. Risk factors for CRAO include high blood pressure, diabetes mellitus, high cholesterol, smoking, and heart disease.
Eyes that have suffered a CRAO are at risk for potentially severe long-term complications. Treatment of these complications is possible and may prevent additional difficulties. Thus, even though there is no effective treatment for the catastrophic vision loss, periodic check-ups are important to identify such complications at an early stage.
Retinal Consultants of Minnesota is a group practice of fellowship trained Retina Specialists. We specialize exclusively in the management of CRAOs and other retinal diseases. We are actively involved in research of new treatments and are capable of rapidly bringing newly approved therapies to our patients.