Central Retinal Artery Occlusion

Central retinal artery occlusion (CRAO) results from obstruction of the central retinal artery, causing inner retinal infarction.¹ Because retinal ganglion cells are, embryologically and functionally, part of the central nervous system, CRAO is best understood as a small-vessel stroke of the eye rather than a purely ophthalmic event.² CRAO comprises four clinically distinct subtypes with markedly different prognoses: non-arteritic CRAO (NA-CRAO), transient NA-CRAO, NA-CRAO with cilioretinal artery sparing, and arteritic CRAO.³

Non-arteritic cases typically involve embolic or thrombotic occlusion, while arteritic CRAO results from inflammatory arteritis (typically giant cell arteritis) affecting the ophthalmic circulation.³ CRAO shares risk factors with systemic vascular disease, and patients face increased risk of ischemic heart disease and cerebral stroke.¹ The classic teaching that irreversible retinal infarction takes 90-240 minutes of complete occlusion has been challenged: because retinal ganglion cells are CNS tissue, infarction may occur after only 12-15 minutes or less of complete non-perfusion, comparable to cerebral ischemia — helping explain why interventions initiated after typical presentation delays are often ineffective. Many CRAOs are incomplete occlusions, though, and may retain a longer window for benefit.⁴

Patients present with sudden, painless, severe monocular vision loss, often to counting fingers or worse.⁵ Spontaneous visual improvement during the first week occurred, among eyes with counting-fingers-or-worse vision at presentation, in 22% of NA-CRAO, 67% of NA-CRAO with cilioretinal sparing, and 82% of transient NA-CRAO — but arteritic CRAO shows no spontaneous improvement at all, underscoring why identifying the subtype (and specifically ruling out arteritis) matters immediately.³

Key differentials: ophthalmic artery occlusion (more severe, both inner and outer retina), branch retinal artery occlusion (sectoral involvement), amaurosis fugax (transient, complete resolution), posterior ischemic optic neuropathy, acute optic neuritis, severe hypertensive retinopathy, retinal vein occlusion (hemorrhagic rather than pale retina), vitreous hemorrhage, and retinal detachment.

Classic findings include a cherry-red spot at the macula (contrast between infarcted pale retina and the still-perfused choroid visible through the thin fovea), diffuse retinal whitening from inner retinal edema, attenuated arterioles, sometimes visible embolic material, and a relative afferent pupillary defect in unilateral cases. Cilioretinal artery sparing shows preserved perfusion in that vessel's distribution when present.³ Urgent evaluation for giant cell arteritis (jaw claudication, scalp tenderness, elevated ESR/CRP) is essential to identify arteritic CRAO.

Unlike ischemic cerebral stroke, there is currently no officially recommended, evidence-based reperfusion treatment for non-arteritic CRAO.¹² Intra-arterial thrombolytic therapy — a natural analogy to stroke care — has been shown in studies to have no beneficial effect and can be harmful, so it should be avoided.³ Conservative therapies have shown limited benefit over the natural course of disease, and while pars plana vitrectomy plus endovascular surgery has drawn interest, it requires further validation before wider adoption.⁵ Management priorities center on urgent triage: rule out arteritic CRAO (which requires immediate systemic corticosteroids to protect the fellow eye and other vascular territories), and — regardless of subtype — investigate and manage the systemic vascular risk that CRAO shares with ischemic heart disease and cerebral stroke.¹³

• CRAO is best conceptualized as a "stroke of the eye," representing small vessel stroke affecting CNS tissue of the retinal ganglion cells^1,2
• The four CRAO subtypes have markedly different prognoses, from 82% spontaneous improvement (transient NA-CRAO) to none (arteritic)³
• Retinal infarction may occur after only 12-15 minutes of complete occlusion, not the traditionally cited 90-240 minutes⁴
• Urgent evaluation for arteritic causes is critical, as arteritic CRAO requires immediate systemic treatment³
• Common pitfall: using intra-arterial thrombolytic agents, shown to be ineffective and potentially harmful³
• Common pitfall: attributing visual improvement to therapeutic interventions without accounting for spontaneous improvement rates^3,5
• Common pitfall: failing to investigate and address underlying systemic vascular risk factors^3,1