CMV Retinitis
On this page
Direct answer
Painless, progressive blurring with new floaters in a patient with AIDS and a CD4 count under 50, and a fundus showing yellow-white necrotic retina with haemorrhage along the vessels — the "pizza-pie" or ketchup-and-cheese appearance — is cytomegalovirus retinitis, the commonest AIDS-related ocular opportunistic infection in the pre-ART era. Induction is ganciclovir 5 mg/kg intravenously twice daily for two to three weeks followed by valganciclovir 900 mg twice daily as maintenance, with foscarnet or cidofovir as alternatives; intravitreal therapy is used when systemic drugs cannot be given, and the durable cure is immune recovery on antiretroviral therapy. The diagnosis is clinical, made on indirect ophthalmoscopy, and every low-CD4 patient with any visual symptom deserves a dilated fundus examination.
What you must remember
- Threshold disease: almost always below CD4 50; CMV retinitis in a patient not known to have HIV is an immediate HIV-testing trigger.
- Symptoms: unilateral floaters, photopsia, painless visual loss or blind spots — characteristically with little pain or redness, because the inflamed eye is an immunosuppressed eye; some patients are screened asymptomatic.
- Fundus signature: confluent yellow-white areas of retinal necrosis with intraretinal haemorrhage spreading along vascular arcades, a granular active advancing "brushfire" edge, and sharp demarcation from destroyed retina; vasculitis may give the frosted-branch pattern.
- Complications: retinal detachment (the late structural sequel), sight-threatening macular or optic nerve involvement, CMV radiculopathy and colitis as concurrent end-organ disease.
- Treatment: ganciclovir 5 mg/kg IV every 12 hours for 14-21 days, then valganciclovir 900 mg twice daily maintenance; ganciclovir causes neutropenia and thrombocytopenia (worse with zidovudine and cotrimoxazole), so monitor counts.
- Alternatives: foscarnet 90 mg/kg twice daily (nephrotoxic, causes ionised hypocalcaemia and genital ulcers), cidofovir (nephrotoxic with uveitis), the ganciclovir implant or intravitreal injections for local therapy, and the combination of ganciclovir plus foscarnet for resistant disease.
- Maintenance withdrawal: valganciclovir can be stopped once the CD4 count is above 100 for three to six months on ART with healed, inactive lesions — parallel to other opportunistic-infection prophylaxis rules.
- Immune recovery uveitis: inflammatory flare with vitritis, cystoid macular oedema and epiretinal membranes after ART-driven CD4 rise — treated with topical or short-course systemic steroids, not by restarting anti-CMV therapy blindly.
- Differential reasoning: painless progressive necrotic retina with little vitritis in the profoundly immunosuppressed versus acute retinal necrosis (varicella or herpes simplex), which is painful with dense vitritis and occurs at higher immune competence; toxoplasma retinochoroiditis gives focal fluffy lesions adjacent to pigmented scars.
How to work through a case step by step
A 28-year-old man, recently found HIV-positive and not yet on ART, reports two weeks of "cobwebs" and a dark crescent in the left visual field; CD4 count is 34. Step one is same-week ophthalmology: the history in a CD4-under-50 patient mandates dilated indirect ophthalmoscopy of both eyes, because lesions begin peripheral and silent, and the contralateral eye is frequently involved. Step two is staging once pizza-pie retinitis is confirmed — distance of the lesion from the macula and optic disc (zone 1 disease threatens vision urgently), and screening for extraocular CMV with a neurological examination and consideration of retinal colitis symptoms. Step three is induction choice: intravenous ganciclovir with twice-weekly blood counts, or oral valganciclovir where adherence and absorption allow; foscarnet is reserved for marrow intolerance with aggressive hydration and electrolyte monitoring. Step four is to begin ART planning within a couple of weeks of anti-CMV control — there is no rationale for prolonged deferral for retinitis alone — while counselling that a new inflammatory floaters-and-blur episode after CD4 recovery may be immune recovery uveitis rather than failure, and that healed retina is structurally fragile. Step five is long-term surveillance: maintenance valganciclovir until CD4 above 100 is sustained, lifetime awareness of retinal detachment risk (flashes and a curtain demand urgent review), and periodic fundoscopy even after stopping maintenance.
Where students slip
The first slip is drug toxicity matching: candidates assign nephrotoxicity to ganciclovir; the mark goes to myelosuppression for ganciclovir and nephrotoxicity (with electrolyte disturbances and genital ulcers) for foscarnet and cidofovir. The second is the "cure" concept — students stop at antivirals, whereas the controlling event is immune reconstitution on ART, and maintenance therapy is a bridge, not a destination. Third is the uveitis trap: new floaters after ART initiation in a healed retina are usually immune recovery uveitis, treated with anti-inflammatory therapy, whereas reactivation of necrosis needs anti-CMV drugs; conflating the two is the planted error in stems. A quiet viva favourite asks why the eye is quiet in CMV retinitis — because profound immunosuppression means minimal vitritis, in contrast to the painful, inflamed eye of acute retinal necrosis.
Frequently asked questions
What fundus appearance is classical of CMV retinitis?
Yellow-white necrotic retina mixed with intraretinal haemorrhage along the vascular arcades — the pizza-pie or ketchup-and-cheese fundus — with a granular active border and sharp demarcation from atrophic retina.
What is the induction and maintenance regimen?
Ganciclovir 5 mg/kg IV twice daily for 14-21 days followed by valganciclovir 900 mg twice daily (or IV ganciclovir) as maintenance; alternatives include foscarnet, cidofovir and intravitreal ganciclovir for selected patients.
When can anti-CMV maintenance therapy be discontinued?
When the CD4 count has remained above 100 cells per microlitre for three to six months on effective ART with inactive, healed lesions — with continued ophthalmic surveillance for detachment.
What is immune recovery uveitis?
A post-ART inflammatory syndrome in eyes with treated CMV retinitis, with vitritis, macular oedema and epiretinal membranes; managed with topical or systemic corticosteroids while confirming the retinitis itself remains inactive.
Which adverse effects distinguish ganciclovir, foscarnet and cidofovir?
Ganciclovir: neutropenia and thrombocytopenia; foscarnet: nephrotoxicity, ionised hypocalcaemia and genital ulceration; cidofovir: nephrotoxicity and uveitis — all requiring the specific monitoring attached to each.