Non-arteritic anterior ischaemic optic neuropathy
A painless stroke of the optic nerve head, often noticed on waking, in people over 50 with vascular risk. Giant cell arteritis is excluded the same day.
What it is
Sudden painless loss of vision in one eye from poor flow in the short posterior ciliary arteries that supply the optic nerve head, usually in a small, crowded disc. It is the most common acute optic neuropathy after 50; the key is to tell it from the arteritic form, which needs urgent corticosteroids.
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Who gets it
Most common acute optic neuropathy after 50; vascular risk factors are frequent.
Causes
- Hypoperfusion of the optic nerve head in a small, crowded disc
- Nocturnal hypotension
Risk factors
- Small optic disc with little or no cup
- Hypertension, diabetes and dyslipidaemia
- Obstructive sleep apnoea
- Nocturnal hypotension, including from over-treated blood pressure
- Phosphodiesterase-5 inhibitors (association reported)
Pathophysiology
In a crowded disc, a drop in perfusion causes ischaemia and swelling of the axons; the swelling compresses neighbouring axons in the tight scleral canal, worsening the damage.
Symptoms and signs
- Sudden painless loss of vision or of the upper or lower half of the field in one eye
- Often noticed on waking
- Reduced colour vision
Diagnosis
- Clinical
- Afferent pupillary defect, altitudinal field defect and a swollen, often segmental disc with nearby haemorrhages; the other eye usually shows a small disc without a cup.
- Tests
- ESR, CRP and blood count the same day to exclude giant cell arteritis; glucose, lipids and assessment for sleep apnoea.
- Imaging
- Brain and orbit MRI if the presentation is atypical.
Differential diagnosis
- Arteritic ischaemic optic neuropathy
- Optic neuritis
- Compressive optic neuropathy
- Papilloedema
Goal of treatment
Exclude giant cell arteritis, control vascular risk factors and protect the other eye.
Treatment
- Medical
- Control of blood pressure (avoiding night-time hypotension), glucose and lipids.
- Follow-up
- Ophthalmology follow-up of visual function and of the other eye.
- Lifestyle
- Assessment and treatment of sleep apnoea.
Complications
- Permanent visual field loss and optic atrophy
- Involvement of the other eye in a minority of patients
Prognosis
Visual loss is usually permanent, with modest improvement in some patients; no treatment has proved to restore vision.
Test yourself
Think of the answer, then tap the question to see it.
Which disease must be excluded the same day in ischaemic optic neuropathy?
Giant cell arteritis, with ESR, CRP and blood count.
What disc anatomy predisposes to the non-arteritic form?
A small, crowded optic disc with little or no cup.
When is the visual loss often noticed?
On waking, consistent with nocturnal hypotension.
Why it happens
In anaesthesia
Connections
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Nonarteritic Anterior Ischemic Optic Neuropathy (StatPearls Publishing (NCBI Bookshelf), 2025).
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Representative model, for educational purposes only.