Intravitreal injection of cidofovir in CMV retinitis

Background: CMV retinitis is the most common opportunistic ocular infection and the main cause of blindness in AIDS patients with a T-helper cell count ≤ 50/μl. Cidofovir is a nucleotide analogue with a long half-life time after phosphorylation intracellularly. It is effective against CMV and can be given intravenously and intravitreally. The aim was to offer an alternative therapy for CMV retinitis to patients who could not receive standard treatment because of contraindications or refused it. The efficacy and tolerance of intravitreal injections of cidofovir should be evaluated. Patients and methods: We treated 16 eyes of 12 patients. The total number of injections with 15 μg of cidofovir each was 49, with an average of 3 injections per eye. The duration of follow-up was 75–295 days (median 170 days). Probenecid was given concomitantly. Injections were repeated after 6–10 weeks. Secondary prophylaxis of CMV organ infection was done with oral ganciclovir. Results: Within a few days all areas with active retinitis turned into scars following the first injection. Under consequent treatment no reactivation was observed. Four eyes developed a mild iritis with hypotony within a mean time of 12 days after injection. All responded rapidly to topical steroids. None had a persisting loss of vision. Two eyes developed cystoid macular edema (CME). Two patients stopped anti-CMV treatment (ganciclovir orally and injections), followed by a recurrence after an average of 64 days. Conclusions: Intravitreal injection therapy with 15 μg cidofovir and concomitant oral probenecid is a valuable and safe alternative treatment for CMV retinitis in AIDS patients. Its main complication is iritis with hypotony, which is effectively treatable with topical steroids. No complications caused by the injection technique itself were noted. The occasional observation of CME in otherwise quiet eyes, however, is probably drug-related.