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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
Key points
- Sudden painless unilateral visual loss — often counting fingers or worse
- Fundoscopy: pale retina with cherry-red spot at macula + RAPD
- Treat as "stroke equivalent" — high risk of stroke within 7 days
- MUST exclude GCA in patients >50 — urgent ESR/CRP, immediate steroids if suspected
- No proven treatment to restore vision once infarction occurs (~90 minutes)
Overview
CRAO occurs when blood flow through the central retinal artery is blocked, causing acute inner retinal ischaemia. Irreversible damage occurs within 60–90 minutes. Causes include thromboembolism (carotid atherosclerosis, cardiac emboli), vasculitis (especially GCA in patients >50), and vasospasm. It is considered a "retinal stroke" sharing the same atherosclerotic risk factors.
Epidemiology
Incidence ~1–2 per 100,000 per year, typically age 60–70 with male predominance. GCA accounts for ~5% of CRAO cases. Risk of ipsilateral stroke within 7 days is ~2–5%.
Clinical Features
Symptoms
Sudden painless monocular visual loss — typically devastating
No pain unless GCA (temporal headache, jaw claudication)
Prior amaurosis fugax may precede
Signs
RAPD
Pale retina with cherry-red spot at macula
Attenuated retinal arteries — "box-carring"
Hollenhorst plaques at arteriolar bifurcations
Investigations
First-line
ESR and CRP (URGENT)MUST exclude GCA
FundoscopyPale retina with cherry-red spot
BP, glucose, lipids, ECGCardiovascular risk assessment and AF screen
Second-line
Carotid duplex ultrasoundIpsilateral carotid stenosis
EchocardiographyCardiac embolic source
CT/MRI brainConcurrent ischaemic stroke
Specialist
Temporal artery biopsyIf GCA suspected — should not delay treatment
Management
RCOphth Guidelines + NICE CKS GCA1
Exclude and treat GCA (age >50)
- If ESR/CRP raised or clinical suspicion: prednisolone 60–80 mg OD immediately
- Temporal artery biopsy within 2 weeks
- GCA treatment protects the FELLOW EYE
2
Stroke pathway and secondary prevention
- Aspirin 300 mg stat, then 75 mg OD
- Atorvastatin 80 mg
- BP control
- Carotid endarterectomy if >50% symptomatic stenosis
- Anticoagulation if AF
Complications
- Permanent visual loss: Most patients have severe irreversible loss
- Neovascular glaucoma: Rubeosis at 2–3 months
- Stroke: 2–5% within 7 days
- Fellow eye involvement in GCA
UKMLA Exam Tips
- 1Sudden painless visual loss + pale retina + cherry-red spot + RAPD = CRAO
- 2Cherry-red spot: fovea has NO inner retinal layers — choroid shows through as red against pale ischaemic retina
- 3ALWAYS check ESR/CRP in patients >50 — GCA needs IMMEDIATE steroids
- 4CRAO = "retinal stroke" — investigate like any acute vascular event
- 5Amaurosis fugax = warning sign before CRAO
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