Central retinal artery occlusion (CRAO) is a major ophthalmological emergency, often described as a \u201cstroke of the eye\u201d.<\/p>\n\n\n\n
The sudden interruption of arterial blood flow to the retina causes an almost immediate loss of visual function in the affected eye, usually without pain, which distinguishes it from other acute ophthalmological conditions.<\/p>\n\n\n\n
Patients typically describe sudden, complete or nearly complete loss of vision in one eye without other accompanying symptoms. In the early stages, the retina appears characteristically pale and white because of ischaemia, with a cherry-red spot at the macula.<\/p>\n\n\n\n
The most common causes are embolism, originating from atherosclerotic plaques, a cardiac source or a thrombus, and local thrombosis. CRAO most often affects older adults with cardiovascular risk factors, although it may also occur in younger people.<\/p>\n\n\n\n
The most critical feature of CRAO is the extremely narrow window for intervention. Experimental data indicate that the retina begins to sustain irreversible injury after only 90 to 100 minutes of complete ischaemia.<\/p>\n\n\n\n
After four hours, the likelihood of meaningful functional recovery declines dramatically. Every minute without treatment therefore increases the risk of permanent visual impairment.<\/p>\n\n\n\n
As in cerebral stroke, tissue surrounding the area of complete ischaemia forms an ischaemic penumbra. This tissue has not yet undergone irreversible injury but is under severe metabolic stress. The affected photoreceptors, amacrine cells and retinal ganglion cells may still be preserved if adequate oxygenation is restored promptly.<\/p>\n\n\n\n
The preservation of this visual penumbra is the central therapeutic objective.<\/p>\n\n\n\n
The Undersea and Hyperbaric Medical Society (UHMS) recognises central retinal artery occlusion as an indication for hyperbaric oxygen therapy, based on clinical studies and case series reporting improvement or preservation of visual acuity in patients treated within the therapeutic window.<\/p>\n\n\n\n
Meta-analyses have suggested better visual outcomes among patients who received hyperbaric oxygen therapy than in historical control groups.<\/p>\n\n\n\n
The biological rationale is clear. Under hyperbaric conditions, plasma oxygen tension rises from approximately 100 mmHg to between 1,500 and 2,000 mmHg. This allows oxygen to reach the retina through diffusion from the vitreous humour, bypassing the obstructed artery entirely.<\/p>\n\n\n\n
At the same time, the vasoconstriction induced in healthy vessels reduces intraocular oedema and may improve tissue perfusion.<\/p>\n\n\n\n
In central retinal artery occlusion, hyperbaric oxygen therapy is used as an emergency adjunctive intervention. The speed at which treatment begins is the most important factor influencing the outcome. Initiation within four to six hours of symptom onset is associated with significantly better results.<\/p>\n\n\n\n
Immediate hyperoxygenation supplies the ischaemic retina with the oxygen required for survival while attempts are made to address the primary vascular obstruction. Anti-apoptotic mechanisms are also activated, delaying neuronal death and providing additional time for effective intervention.<\/p>\n\n\n\n
Alongside hyperbaric oxygen therapy, the ophthalmologist assesses and applies appropriate ophthalmological procedures, which may include ocular massage, anterior chamber paracentesis or thrombolytic treatment.<\/p>\n\n\n\n
The intensive treatment course typically consists of 10 to 15 daily sessions during the acute phase.<\/p>\n","protected":false},"excerpt":{"rendered":"
Central Retinal Artery Occlusion Central retinal artery occlusion (CRAO) is a major ophthalmological emergency, often described as a \u201cstroke of the eye\u201d. The sudden interruption … <\/p>\n