PURPOSE: To evaluate the decrease in intraocular pressure associated with cidofovir (1-[(S)-3hydroxy-2. (phosphonomethoxy)propyl]cytosine dihydrate; HPMPC) intravitreal injections. METHODS: We followed up 97 eyes of 63 patients with acquired immunodeficiency syndrome (AIDS) who had cytomegalovirus retinitis and had been treated with up to nine 20-μg intravitreal cidofovir injections. Measurements were taken at baseline, between 2 and 3 weeks, and at 5 to 6 weeks after injections. Anterior chamber fluorophotometry was studied in seven eyes (four patients) before and after injections. Ciliary body anatomy was evaluated in two patients. RESULTS: After the first intravitreal injection, mean intraocular pressure was 2.2 mm Hg lower than that at baseline at 2 to 3 weeks (P < .001) and 1.3 mm Hg lower than at baseline at 5 to 6 weeks (P = .0025). After the second injection, mean pressure was 2.6 mm Hg lower at 2 to 3 weeks (P = .0013) and 1.5 mm Hg lower at 5 to 6 weeks (P = .043). After subsequent injections, however, the decrease was less than 1 mm Hg, suggesting that a plateau had been reached. Pressure in eyes with anterior uveitis after the first injection was lower than that in eyes without anterior uveitis (P < .0001). The mean rate of aqueous flow decreased from 2.8 to 1.9 μl per minute 2 to 4 weeks after injection (P < .015). Ultrasound biomicroscopy disclosed that severe hypotony after cidofovir injections is associated with ciliary body atrophy. CONCLUSIONS: Intraocular pressure decreases after the initial 20-μg cidofovir intravitreal injection. However, eyes stabilize (pressure plateaus) after three injections. Effects on the ciliary body are the main cause of the decrease after cidofovir injections.
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