A 41-year-old man with HIV (CD4 count 24 cells/µL, not on antiretroviral therapy) presents with 2 weeks of floaters, blurred vision, and a painless paracentral scotoma in the right eye. Dilated fundus examination reveals confluent yellow-white areas of full-thickness retinal necrosis along the superior vascular arcade with fluffy granular borders, prominent hemorrhages, and vessel sheathing — the classic "pizza pie" appearance. Mild vitritis is noted. The lesion marked **B** in the diagram is identified. Which of the following is the most appropriate INDUCTION therapy for this sight-non-threatening peripheral disease?
A. Intravenous foscarnet 90 mg/kg twice daily for 2 weeks
B. Ganciclovir intravitreal implant (Vitrasert) with systemic cidofovir
C. Intravitreal ganciclovir 2 mg twice weekly combined with systemic valganciclovir
D. Oral valganciclovir 900 mg twice daily for 14–21 days
Explanation
Why oral valganciclovir 900 mg twice daily for 14–21 days is correct
The clinical presentation — confluent yellow-white retinal necrosis with hemorrhage, minimal vitritis, and CD4 <50 cells/µL — is pathognomonic for CMV retinitis (structure B). The IDSA HIV OI Guidelines 2024 and AAO BCSC specify that for sight-non-threatening disease (peripheral, away from the optic nerve and macula), oral valganciclovir 900 mg twice daily for 14–21 days is the preferred induction regimen due to excellent oral bioavailability, cost-effectiveness, and ease of administration. This patient's lesion is along the superior vascular arcade, away from the fovea and optic nerve head, making it suitable for oral therapy alone.
Why each distractor is wrong
Intravitreal ganciclovir 2 mg twice weekly combined with systemic valganciclovir: This is reserved for sight-threatening ZONE 1 disease (within 1500 µm of the fovea or optic nerve head). The patient's peripheral location does not warrant intravitreal injection, which carries risks of endophthalmitis and retinal detachment.
Intravenous foscarnet 90 mg/kg twice daily for 2 weeks: IV foscarnet is used for ganciclovir-resistant CMV (UL97 mutations) or in cases of severe neutropenia. It is not first-line induction therapy and carries significant nephrotoxicity and electrolyte disturbances.
Ganciclovir intravitreal implant (Vitrasert) with systemic cidofovir: The Vitrasert implant is now largely historical and reserved for highly selected cases. Cidofovir is nephrotoxic and requires probenecid co-administration; it is not standard induction therapy for newly diagnosed CMV retinitis.
High-YieldNEET PG
CMV retinitis with CD4 <50 cells/µL and minimal vitritis (due to impaired immune response) is treated with oral valganciclovir for peripheral disease; intravitreal therapy is reserved for sight-threatening (Zone 1) lesions near the macula or optic nerve.
IDSA HIV OI Guidelines 2024; AAO BCSC Uveitis Section 9 2024
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