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NAION — RACP Adult Medicine MCQ

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ModerateGeneral Internal MedicineNAIONRACP Adult Medicine

A 60-year-old woman presents with sudden onset painless visual loss in her left eye. Fundoscopy shows a pale, swollen optic disc with a small cup-to-disc ratio in the fellow eye. She has a history of hypertension and sleep apnoea. ESR and CRP are normal. What is the most likely diagnosis?

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Correct answer: A — Optic neuritis

NAION presents with sudden, painless, monocular visual loss in patients with cardiovascular risk factors. The hallmark is a swollen optic disc with a 'disc at risk' (small cup-to-disc ratio) in the fellow eye. Normal inflammatory markers (ESR, CRP) distinguish it from arteritic AION (GCA). There is no proven treatment for NAION. Risk factor modification and treating obstructive sleep apnoea (a recognised risk factor) are important. The visual prognosis is variable.

Reference: eTG – 2025 – Neurology