What happens
Retinal arteries and veins share a sheath where they cross. A hardened artery can compress the vein at a crossing, or the central vein can be narrowed where it leaves the optic nerve, and blood flow slows until a clot forms. Behind the blockage, pressure rises, capillaries leak, and the retina fills with hemorrhages and fluid. If the affected area includes the macula, it swells and central vision blurs. In severe occlusions the retina is starved of oxygen and may later grow abnormal vessels, as in diabetic retinopathy.
Branch and central occlusion
A branch retinal vein occlusion blocks a vein draining one quadrant, and its effect on vision depends on whether that quadrant includes the macula; many are mild. A central retinal vein occlusion blocks the main vein and affects the whole retina; vision loss is usually greater and the risk of complications higher. Both are diagnosed at a dilated examination and characterized with OCT and, by a retina specialist, angiography.
What it says about your health
Vein occlusion is a vascular event, and it shares risk factors with stroke and heart disease. A diagnosis is followed by a review with your primary care doctor of blood pressure, blood sugar, cholesterol and, in younger patients, clotting disorders and inflammatory conditions. Glaucoma, which raises pressure inside the eye and slows venous outflow, is checked and treated. Managing these reduces the risk to the other eye.
Treatment
The blockage itself cannot be removed. Treatment addresses its consequences. Macular edema, the main cause of vision loss, is treated with anti-VEGF injections into the eye, repeated at intervals, which reduce swelling and improve vision in many patients; steroid implants are an alternative. If the retina grows abnormal vessels, laser treatment prevents bleeding and a particularly serious form of glaucoma. We diagnose vein occlusion, image the macula, coordinate the health review, and refer to a retina specialist for injections, co-managing your care.
Outlook
Branch occlusions often recover well, particularly with treatment of any macular swelling. Central occlusions vary: those with good blood flow remaining recover reasonably, while those with extensive closure of capillaries recover less. Treatment continues for months to years and monitoring for life, and the other eye is examined regularly.
Is this right for your eyes?
Nothing on this page is a diagnosis. Whether this is what is affecting your vision is decided by a full examination at one of our 4 offices: Pasadena, Huntington Beach, Woodland Hills and Beverly Hills.
About this content: This page was written with the assistance of AI tools and reviewed for medical accuracy by Dr. Bavand Youssefzadeh, DO. It is general information, not medical advice, and does not replace an eye examination. Individual results vary. Read our medical disclaimer.
