What Is Retinal Vessel Occlusion?

Retinal vessel occlusion is a blockage in one of the major arteries or veins of the retina—the layer of light-sensitive cells lining the back surface of the eye. These blockages are more common among older individuals.

Occlusion of the central retinal artery (CRAO) produces sudden, painless vision loss and is a sight-threatening emergency. If blood flow is not reestablished within a few hours, death of the light-sensitive cells produces permanent vision loss in the affected eye.

Most blockages are caused by a blood clot formed at the site or by a fragment of atherosclerotic plaque (embolus) that broke away from its original site and traveled through the bloodstream to lodge in the retinal artery. Blockage in the central retinal artery or any of its branches will choke off the blood supply to the affected eye or affected portion of the retina.

By contrast, sudden occlusion or obstruction of the central retinal vein (CRVO) is not a medical emergency—though it too warrants prompt evaluation. In retinal vein occlusion, a vessel that normally drains blood from the retina becomes blocked, causing fluid and blood to build up in the retina. The higher the grade of the obstruction, the greater the degree of visual disturbance. In some cases, vision may clear spontaneously, though typically some degree of vision impairment remains.

In both retinal artery and retinal vein occlusion, temporary episodes of partial vision loss may precede the event. Because the cause needs to be identified, all cases of sudden vision loss require immediate attention.

What Causes Retinal Vessel Occlusion?

  • Arterial occlusions are generally caused by a blood clot, most often a piece of atherosclerotic plaque (embolus) that traveled to the site. Inflammatory conditions such as giant cell (temporal) arteritis can also produce retinal artery occlusions.
  • Venous occlusions are caused by thrombus (clot) in the lumen of a vein.
  • Other conditions, such as high blood pressure, diabetes mellitus, glaucoma, carotid artery disease and hyperviscosity syndromes are also associated with retinal vessel occlusion.
  • Smoking can also result to retinal vessel occlusion.

Symptoms of Retinal Vessel Occlusion


  • Sudden loss of vision in one eye. Vision loss may be complete or partial, affecting a limited area of the visual field.

Retinal Vessel Occlusion Prevention

  • While there is no definitive way to prevent retinal vessel blockage, regular eye exams may aid in early detection of potential disorders.
  • Controlling the blood pressure prevents the arteries from getting harder. It also prevents a blockage of the vein in the other eye.
  • Eat a low fat diet.
  • Do not smoke. Smoking hardens all the arteries.
  • Exercise regularly.
  • Use aspirin to prevent further blockages and heart diseases. However, aspirin is not advisable for patients who have peptic ulcer or indigestion (clopidrogel). It is better to consult your doctor.
  • Overweight individuals should try to lose weight.

Retinal Vessel Occlusion Diagnosis

  • Requires dilated eye exam by an ophthalmologist.
  • Complete patient history and physical examination may be needed to diagnose the underlying cause.

How to Treat Retinal Vessel Occlusion

Arterial occlusions:

  • A doctor may apply firm, intermittent pressure to the eye with the heel of the hand (pressing on the eye for a few seconds, suddenly releasing the pressure, then repeating the procedure), in an attempt to dislodge the blockage.
  • Medications can be used or a small amount of fluid may be withdrawn from the front of the eye to suddenly lower eye pressure in hopes of propelling the blockage downstream to smaller vessels.
  • Intra-arterial injection of clot-busting drugs may be attempted to try and restore circulation and sight.
  • Anticoagulant drugs, such as aspirin, heparin, or warfarin, may be administered to prevent further clot formation in some cases.

Venous occlusions:

  • Ophthalmologists may use laser surgery to reverse vision loss from chronic swelling of the retina or to promote the regression of abnormal blood vessels that may arise as a complication of the disorder.
  • Several surgical procedures aimed at reducing the obstruction are presently under investigation.
  • Drugs may be used to treat associated glaucoma.

When to Call a Doctor

  • EMERGENCY Call an ambulance or see an ophthalmologist immediately if you experience sudden and profound vision loss.


Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference

Simeon Margolis, M.D., Ph.D., Medical Editor

Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at Healthcommunities.com

Published: 30 Jan 2012

Last Modified: 17 Mar 2015