What it is
Central retinal artery occlusion (CRAO) is a stroke of the eye — a clot blocks the artery feeding the retina, causing sudden, painless vision loss in one eye. Retinal tissue starts dying within about 90 minutes.
How hyperbaric oxygen helps
The retina has a backup: the choroid layer behind it can supply oxygen by diffusion if blood oxygen is high enough. HBOT raises dissolved oxygen enough to keep the retina alive while the blockage resolves or treatment restores flow — buying time for vision that would otherwise be lost.
What treatment looks like
Genuinely urgent: best results come when HBOT starts within hours of vision loss. Protocols run 2.0–2.8 ATA, often multiple sessions over the first days.
- Sudden painless vision loss = emergency room first, immediately.
- Ask the ER about hyperbaric availability — minutes matter.
- FDA-recognized indication.
The evidence, honestly
Grade B — Good Evidence
Meaningful clinical studies support benefit; more trials would strengthen certainty.
Our structured research library — with every study linked from this page — arrives with the next site update. Ask us for the citations any time in the meantime.
Common questions
How fast do I need to act?
Immediately. Retinal cells begin dying within about 90 minutes of blockage. Go to the ER now; HBOT started within the first hours offers the best chance of preserving vision.
Educational content, not medical advice — see our medical disclaimer. *Medicare coverage requires meeting clinical criteria; we verify yours for free. Last medically reviewed July 2026 by Dr. David Greene, MD.