A 55-year-old immunocompetent woman develops rapidly progressive pain, redness, floaters, and severe visual loss over four days. Fundoscopy shows confluent yellow-white necrotizing retinitis with sharply demarcated borders starting at the periphery and progressing circumferentially, marked retinal arteriolar occlusion and sheathing, dense vitritis, and early inferior retinal detachment. The most likely causative agent is:

• A Toxoplasma gondii
• B Cytomegalovirus
• C Varicella-zoster virus or herpes simplex virus ✓
• D Mycobacterium tuberculosis

Explanation

Acute retinal necrosis is defined by the triad of one or more foci of well-demarcated peripheral necrotizing retinitis progressing rapidly without antiviral therapy, rapid progression in the absence of antiviral therapy, and occlusive vasculopathy with arterial involvement, occurring mainly in immunocompetent individuals. It is caused by alpha-herpesviruses, chiefly varicella-zoster virus, followed by herpes simplex virus types 1 and 2. CMV retinitis occurs in the profoundly immunosuppressed, is more indolent and granular, and lacks prominent arterial occlusion.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.