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Optic Neuritis — RACP Adult Medicine MCQ

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EasyNeurologyOptic NeuritisRACP Adult Medicine

A 30-year-old woman presents with painful monocular visual loss in the left eye worse on eye movement. She has a relative afferent pupillary defect and impaired colour vision (red desaturation). The optic disc appears swollen. Visual acuity is 6/36. MRI shows optic nerve enhancement. What is the most likely diagnosis?

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Correct answer: D — Optic neuritis

Painful monocular visual loss (worse with eye movement), RAPD, dyschromatopsia (red desaturation), optic disc swelling, and optic nerve enhancement on MRI in a young woman is classic for optic neuritis. It is often the presenting feature of MS. Treatment is IV methylprednisolone if severe. MRI brain should be performed to assess for demyelinating lesions.

Reference: ABN/MSA – 2024 – Optic Neuritis Guidelines