An “eye stroke” occurs when blood flow to the retina, the light-sensitive tissue at the back of the eye, is blocked. This blockage deprives retinal cells of oxygen and nutrients, causing vision loss. Like a brain stroke, it’s a medical emergency requiring immediate attention to protect sight. Eye strokes involve various blockages within the eye’s vascular system.
Understanding Eye Strokes
Eye strokes involve two main conditions: Retinal Artery Occlusion (RAO) and Retinal Vein Occlusion (RVO). In RAO, an artery supplying blood to the retina is blocked, often by a blood clot or fatty plaque. This can occur in the central retinal artery (CRAO) or a smaller branch (BRAO). The sudden lack of blood supply leads to rapid, severe vision loss.
Conversely, RVO occurs when a retinal vein is blocked, typically by a blood clot. This prevents blood drainage, causing fluid and pressure buildup. RVO can affect the central retinal vein (CRVO) or a smaller branch (BRVO). Resulting fluid leakage and swelling, especially in the macula, can distort vision. While both are eye strokes, the affected vessel (artery or vein) and damage mechanism (ischemia vs. fluid buildup) differentiate them.
Recognizing the Signs
Eye stroke symptoms often appear suddenly and are painless. A person may experience rapid blurring or partial to complete vision loss in one eye. This can range from a subtle blind spot to a significant darkening or shadow across the visual field.
Specific visual disturbances include grey spots or “floaters” (small dark shapes that drift across the eye). Vision may also become distorted, appearing wavy or out of shape. Symptoms usually have a sudden onset but can develop gradually over hours or days. Immediate medical attention is recommended for any sudden vision changes, as prompt treatment can help prevent permanent vision loss.
Causes and Risk Factors
Eye strokes are linked to systemic health conditions affecting blood vessels. High blood pressure (hypertension) is a common risk factor, damaging delicate eye blood vessels and contributing to blockages. Diabetes can also harm small retinal blood vessels, increasing eye stroke likelihood.
High cholesterol levels can lead to fatty plaque buildup in arteries, which may break off and travel to the eye, causing arterial blockage. Other factors include atherosclerosis (hardening and narrowing of arteries) and heart conditions like atrial fibrillation, which can form blood clots. Glaucoma, characterized by increased eye pressure, also elevates risk. Blood clotting disorders and carotid artery disease (narrowing of neck arteries) further increase susceptibility.
Diagnosis and Treatment
Diagnosing an eye stroke involves medical procedures performed by an ophthalmologist. A comprehensive eye exam is the first step, including checking visual acuity and a dilated eye exam for a detailed view of the retina and optic nerve. Optical Coherence Tomography (OCT) is used to detect retinal swelling (macular edema) and visualize retinal layers.
Fluorescein angiography is another diagnostic tool. This involves injecting a yellow dye into a vein and taking photographs as it travels through retinal blood vessels. This imaging identifies blocked vessels, poor blood flow, and leakage. For Retinal Artery Occlusions, treatments may include ocular massage to dislodge a clot, or procedures to reduce intraocular pressure, such as anterior chamber paracentesis (fluid removal from the front of the eye). Breathing a mixture of oxygen and carbon dioxide (carbogen) may also be used to widen retinal arteries.
Treatment for Retinal Vein Occlusions focuses on managing complications like macular edema and abnormal new blood vessel growth (neovascularization). Anti-VEGF (anti-vascular endothelial growth factor) injections are administered directly into the eye to reduce swelling and inhibit the growth of these vessels. Corticosteroid injections can also reduce inflammation and swelling. Laser therapy, specifically panretinal photocoagulation, may address abnormal blood vessels that can lead to bleeding or increased eye pressure. Treatment effectiveness depends on how quickly it is initiated after symptoms appear.
Prevention Strategies
Reducing eye stroke risk involves managing underlying health conditions and adopting healthy lifestyle choices. Maintaining healthy blood pressure through diet, exercise, and medication is a primary preventative measure. For diabetics, controlling blood sugar levels is important, as uncontrolled diabetes can damage retinal blood vessels.
Managing cholesterol levels through a balanced diet and regular physical activity can prevent plaque buildup in arteries. Quitting smoking is recommended, as tobacco use increases the risk of blood clot formation and vascular disease. Regular eye examinations allow eye care providers to monitor eye health and detect early signs of issues, enabling timely intervention and risk factor management.