A 48-year-old immunocompetent man presents with rapidly progressive visual loss in the left eye. Fundoscopy shows confluent yellow-white necrotising lesions with discrete borders in the peripheral retina, occlusive retinal vasculitis along the arcades, and dense vitritis. Polymerase chain reaction of aqueous humour is most likely to identify which organism?

• A Varicella-zoster virus ✓
• B Toxoplasma gondii
• C Treponema pallidum
• D Mycobacterium tuberculosis

Explanation

The American Uveitis Society diagnostic triad of acute retinal necrosis comprises one or more foci of retinal necrosis with discrete borders in the peripheral retina, rapid progression in the absence of antiviral therapy, and circumferential spread, together with occlusive vasculopathy and a prominent inflammatory reaction in the vitreous and anterior chamber. Varicella-zoster virus is the commonest cause, followed by herpes simplex virus. Toxoplasmic retinochoroiditis typically shows a single focal lesion adjacent to an old pigmented scar rather than confluent peripheral necrosis.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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