A 60-year-old hypertensive man wakes up with sudden loss of vision in the right eye. Visual acuity is counting fingers. There is a relative afferent pupillary defect (RAPD) on the right. Fundoscopy shows an oedematous, pale disc with flame-shaped haemorrhages at the disc margin. The most likely diagnosis is:

• A Posterior ischaemic optic neuropathy
• B Central retinal vein occlusion
• C Optic neuritis
• D Non-arteritic anterior ischaemic optic neuropathy (NAION) ✓

Explanation

Non-arteritic anterior ischaemic optic neuropathy (NAION) is the most common acute optic neuropathy in patients over 50 years. It is caused by infarction of the anterior optic nerve head supplied by the posterior ciliary arteries. Characteristic features include painless acute visual loss on waking, RAPD, disc oedema with peripapillary haemorrhages, altitudinal visual field defect (inferior > superior), and a small crowded optic disc (small cup-to-disc ratio, 'disc at risk'). There is no proven treatment.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.