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Blockage of Central Retinal Arteries and Branch Retinal Arteries

(Central Artery Occlusion, Branch Artery Occlusion)


Sonia Mehta

, MD, Vitreoretinal Diseases and Surgery Service, Wills Eye Hospital, Sidney Kimmel Medical College at Thomas Jefferson University

Reviewed/Revised Apr 2022 | Modified Sep 2022
Topic Resources

An artery in the retina (the transparent, light-sensitive structure at the back of the eye) may become blocked, causing sudden, painless loss of vision.

  • Doctors typically make the diagnosis by looking in the eye with an ophthalmoscope and sometimes by testing.

  • Treatments are usually unsuccessful in restoring vision.

The central retinal artery is the main vessel that supplies blood to the retina. This artery can become completely blocked by an embolism or thrombosis (formation of a blood clot in the artery). Blockage may occur in the main artery or in its branches.

The Retina and Optic Nerve

Sometimes the cause of the blockage is unknown.


The affected eye has a sudden and severe but painless loss of vision over the entire field of vision. Sometimes only a part of the field of vision is affected.

Blockage of the central retinal artery may also cause growth of abnormal blood vessels on the retina or iris. Sometimes these abnormal blood vessels bleed or cause a painful type of glaucoma (called neovascular glaucoma). In neovascular glaucoma, abnormal blood vessels that have formed in the iris close the space between the iris and the cornea, blocking the drainage of fluid from the eye and causing buildup of pressure in the eye (glaucoma Glaucoma Glaucomas are a group of eye disorders characterized by progressive optic nerve damage (often, but not always, associated with increased eye pressure) that can lead to irreversible loss of vision... read more ).


  • A doctor's examination of the eye

  • Fluorescein angiography

  • Optical coherence tomography

  • Sometimes echocardiography, Doppler ultrasonography, and/or blood tests

Using an ophthalmoscope, doctors can see changes in blood vessels and the retina. If the central retinal artery is blocked, the retina may appear pale.

If people experience sudden brief loss of vision in one eye and doctors think this is due to a clot that is blocking the retinal artery, treatment is started immediately rather than delayed for imaging studies.


If the blockage occurred in a branch of the central retinal artery, people may maintain good to fair vision.

If the blockage occurred in the central retinal artery itself, vision loss is often profound, even with treatment.

Once the retinal tissue becomes permanently damaged, which can happen as quickly as 90 minutes after the blockage, vision loss is usually permanent.

If giant cell arteritis Giant Cell Arteritis Giant cell arteritis is chronic inflammation of large and medium arteries of the head, neck, and upper body. Typically affected are the temporal arteries, which run through the temples and provide... read more is the cause of the retinal artery blockage, prompt diagnosis and treatment may allow people to regain some lost vision and be protected from damage to the other eye.

People with retinal artery occlusion may have blockages affecting other arteries that supply the brain. These blockages increase the risk of stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction). Symptoms occur suddenly... read more , particularly in the weeks following a central retinal artery occlusion.


  • Prevention by controlling risk factors

  • Sometimes measures to lower pressure in the eye, including eyedrops, eye massage, or removing fluid from the eye with a needle

  • Sometimes laser treatment of abnormal or bleeding blood vessels

  • For giant cell arteritis, corticosteroids

Because treatments tend not to be effective, preventing such blockages by controlling risk factors (for example, high blood pressure, diabetes, and other risk factors for atherosclerosis) is desirable.

When blockage of a central retinal artery does occur, immediate treatment is often given in an attempt to unblock the retinal artery. However, treatments are rarely effective. Pressure inside the eye sometimes can be lowered by giving drugs that lower blood pressure (such as timolol eye drops or acetazolamide taken by mouth).

Lowering the pressure inside the eye by massage or by anterior chamber paracentesis may dislodge a blood clot or embolus and allow it to enter a smaller branch of the vessel, thereby reducing the area of damage to the retina.

People with suspected giant cell arteritis are given high-dose corticosteroids either by mouth or by vein as soon as possible.

Laser treatment may be used to destroy abnormal blood vessels to treat or prevent neovascular glaucoma, prevent further vision loss from bleeding within the eye, or both. However, treatment of neovascular glaucoma is difficult.

Because people with central artery occlusion have an increased risk of stroke, doctors immediately refer them to a specialized stroke center for further evaluation.

More Information

The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

    • National Eye Institute: A resource for learning about eye health (in English and Spanish) for adults and children, as well as access to outreach campaigns.

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