Central Retinal Artery Occlusion (CRAO)

Hyperbaric Oxygen Therapy Approval Status

Yes Clearance by US Food and Drug Administration (FDA)

Yes Approval by the Undersea and Hyperbaric Medical Society (UHMS)

About Clearance and Approval


Definition and Causes

Central retinal artery occlusion (CRAO) is a blockage in one of the small arteries that supply blood to the retina of the eye. The retina is the back wall of the eye that senses light and transmits images to the brain. People with CRAO experience sudden blindness, blurring, or partial loss of vision. The vascular event is usually brief and painless, but retinal damage and impaired vision may be permanent.

Artery blockages, or occlusions, are caused by clots or fat deposits circulating with the blood. Hardening of the arteries (arterio- or atherosclerosis) and other cardiovascular diseases greatly increase the risk. CRAO may also be an early warning sign of stroke, heart attack, or other life-threatening medical emergencies.

As a vascular event, CRAO differs from retinitis pigmentosa, macular degeneration, macular edema, and other progressive diseases of the retina.

Evidence Index

FDA cleared, widely reimbursed
Strong body of evidence
Repeatedly favorable results
Early or mixed results
Unfavorable or no evidence
Strong evidence against HBOT

Treatment with Hyperbaric Oxygen Therapy

Hyperbaric oxygen therapy (HBOT) is one of the few treatments proven effective for central retinal artery occlusion. Physicians may also use intravenous (IV) and topical medications or carbogen therapy, a combination of carbon dioxide and oxygen gas, to reduce pressure and increase blood circulation in the eye. CRAO is a vascular event requiring speedy attention. Proper treatment in the first 24 hours is critical.

Read the Arterial Insufficiencies: Central Retinal Artery Occlusion page in the Undersea and Hyperbaric Medical Society resource library to learn more about CRAO, the rationale for hyperbaric oxygen therapy, and clinical outcomes and success factors.

HyperbaricLink Commentary

The retina consumes oxygen at a rate faster than any other organ in the body. It is highly sensitive to ischemia, or lack of blood supply. In the treatment of CRAO hyperbaric oxygen therapy has succeeded where others in the last 100 years have failed [ UHMS ]. But quick access to an emergency-ready chamber is a must. Or as [ Medscape ] puts it, “Hyperbaric oxygen therapy (HBOT) may be beneficial if begun within 2-12 hours of symptom onset. Institute treatment with other interventions first, as transport to a chamber may usurp precious time.” Central retinal artery occlusion offers yet another good reason, then, for the healthcare community to demand 24/7 access to hyperbaric medicine.

Patient Resources

HyperbaricLink recommends the following websites for anyone seeking authoritative information, patient advocacy, and community support for central retinal artery occlusion, eye disease, and vision loss.


A service of the US National Library of Medicine and the National Institutes of Health, MedlinePlus offers plenty of helpful links from its easy-to-read article on retinal artery occlusion.

National Federation of the Blind

The “Voice of the Nation’s Blind,” with more than 50,000 members, the NFB is a leading source of information about vision loss and a strong force in advocacy, education, research, technology, and programs to improve blind people’s lives.

Prevent Blindness America

A volunteer eye health and safety organization dedicated to fighting blindness and saving sight, Prevent Blindness America provides vision screening, education, advocacy, and research support.


The central retinal artery entry in Wikipedia provides some basic information about CRAO, with a few nice photographs and medical illustrations of the eye.

Clinical Resources

Start with the following resources to explore current research activities and the peer-reviewed medical literature on hyperbaric oxygen therapy for central retinal artery occlusion (CRAO).

 Use the search buttons below to go directly to research on hyperbaric oxygen therapy.

National Institutes of Health

ClinicalTrials.gov keeps the official list of human clinical trials currently enrolling, in progress, and recently completed. One may reasonably question the size and legitimacy of any study not listed here.

Search ClinicalTrials.gov

Google Scholar

A specialized Google search engine, Google Scholar indexes scholarly articles, patents, and legal opinions and journals. Google Scholar may produce many search results, but entries provide easy access to full-text journal articles.

Search Google Scholar


HBOEvidence uses computerized tools to appraise the key randomized controlled trials (RCTs) in the hyperbaric medical literature. One may reasonably question the overall strength of HBOT evidence for any disease or condition not covered here.

Search HBOEvidence


A service of WebMD, Medscape offers specialists, primary care physicians, and other health professionals robust and integrated medical information and educational tools.

Read the Medscape article Central Retinal Artery Occlusion

US National Library of Medicine, US National Institutes of Health

PubMed keeps the official list of scientific papers published in reputable peer-reviewed medical journals. One may reasonably question the importance and legitimacy of any study not listed here.

Search PubMed.gov


News About Central Retinal Artery Occlusion and Hyperbaric Oxygen Therapy

In the News: Hyperbaric Oxygen Therapy for Leber Hereditary Optic Neuropathy (LHON)?

Wednesday, 6/6

Today the National Hyperbaric Centre of Dublin, Ireland, reports success in using hyperbaric oxygen therapy (HBOT) to save the eyesight of a young man with Leber hereditary optic neuropathy (LHON), a mitochondrial disease that u read more...

More news from O2.0 – the HyperbaricLink blog

Complete central retinal artery occlusion news archive from O2.0 — the HyperbaricLink blog

Further Reading

HyperbaricLink suggests
The Mind's Eye (unabridged audiobook)
by Oliver Sacks
(Random House Audio, 2010).

A Leg to Stand On cover

Related Terms

  • Arterial insufficiencies
  • Atherosclerosis
  • Blindness
  • Blood clot
  • Carbogen therapy
  • Eye disease
  • Glaucoma
  • Heart attack
  • Hypoxia
  • Ischemia
  • Macular degeneration
  • Macular edema
  • Ophthalmology
  • Retinitis pigmentosa
  • Stroke
  • Vascular event
  • Vision loss


Undersea and Hyperbaric Medical Society, HBO Indications, Arterial Insufficiencies: Central Retinal Artery Occlusion. Retrieved 02 May 2015.
MedlinePlus, US National Library of Medicine, National Institutes of Health, Retinal artery occlusion. Retrieved 31 August 2011.
Page Data
Updated: 24 Jul 2015 04:43 PM
Created: 31 Aug 2011 05:12 PM
By: About the authors »