AKT · Ophthalmology/Neuro-ophthalmology

Ischaemic optic neuropathy (AION) & amaurosis fugax

Infarction of the optic nerve head — arteritic (GCA) vs non-arteritic; transient retinal ischaemia

Overview

Infarction of the anterior optic nerve head causing sudden, painless, often altitudinal visual loss with a swollen disc. Arteritic AION is due to giant cell arteritis (an emergency — bilateral blindness risk); non-arteritic AION occurs in small 'disc-at-risk' eyes with vascular risk factors. Amaurosis fugax (transient monocular 'curtain') is a TIA-equivalent warning of carotid/cardiac embolism or GCA.

Recognise

Sudden painless visual loss, often ALTITUDINAL (lower or upper half), with a swollen optic disc and RAPD
Arteritic (GCA): age >50, jaw claudication, scalp tenderness, headache, malaise, raised ESR/CRP, often a chalky-white swollen disc; fellow eye at imminent risk
Non-arteritic: smaller 'crowded' disc, vascular risk factors (hypertension, diabetes), nocturnal hypotension; amaurosis fugax = transient curtain over vision (embolic or GCA)

Red flags

Any visual loss/amaurosis with GCA features ≥50 yrs → immediate high-dose steroids + same-day referral, do not wait for biopsy — the other eye can be lost within days
Amaurosis fugax = TIA → urgent TIA pathway (carotid imaging, antiplatelet, vascular risk)

Differentials & how to tell them apart

Central retinal artery occlusionpale retina with cherry-red spot rather than a swollen disc; also exclude GCA

Optic neuritisyounger, PAINFUL on eye movement, recovers; AION is older, painless, altitudinal

Retinal detachmentflashes/floaters and a curtain with an elevated retina

Papilloedemabilateral disc swelling from raised ICP, vision preserved early

Investigations

URGENT ESR/CRP (± platelets) for GCA; temporal artery ultrasound (halo sign)/biopsy. Fundoscopy (swollen disc), fields (altitudinal). For amaurosis: carotid Doppler, ECG/echo, vascular risk profile.

Management

Arteritic (GCA) → immediate high-dose steroids; non-arteritic/amaurosis → vascular risk management

1Determine arteritic vs non-arteritic. ≥50 with GCA features or amaurosis: urgent ESR/CRP and SAME-DAY ophthalmology.Gate: If GCA is suspected, START high-dose corticosteroids IMMEDIATELY (before temporal artery biopsy) — delay risks blindness in the fellow eye within days; biopsy stays positive for ~1–2 weeks after starting steroids
2Arteritic: confirm with temporal artery US/biopsy, steroid taper with bone/GI protection, rheumatology follow-up (cross-ref the GCA card on neurology). Non-arteritic/amaurosis fugax: TIA-style vascular secondary prevention (antiplatelet, statin, BP, carotid imaging).

High-dose corticosteroid — arteritic (GCA): IV methylprednisolone or oral prednisolone 40–60 mg immediately to protect the fellow eye

Antiplatelet + vascular secondary prevention — non-arteritic AION/amaurosis fugax — manage vascular risk (as for TIA)

Key points

Sudden painless altitudinal loss + swollen disc + age >50 = AION — check ESR/CRP and steroid first if GCA is possible. Amaurosis fugax is a TIA of the eye: treat the patient as a stroke risk. (GCA itself is carded on neurology.)

Monitor & prognosis

Fellow eye; ESR/CRP and steroid taper in GCA; vascular risk otherwise.

Visual loss usually permanent; treatment protects the fellow eye / prevents stroke.

Source: NICE CKS Giant cell arteritis; BSR GCA guideline; RCOphth