Purpose To determine the efficacy of anterior chamber decompression in the management of intraocular pressure (IOP) spikes in the early period after uneventful phacoemulsification. Setting Royal Free Hospital, Department of Ophthalmology, Royal Free and University College London Medical School, London, United Kingdom. Methods This prospective case series comprised 11 consecutive patients with otherwise healthy eyes who an IOP of at least 40 mm Hg 4 to 6 hours after phacoemulsification. After anterior chamber decompression, the IOP was measured at 0, 15, 30, 45, and 60 minutes or until it exceeded 40 mm Hg. Results The mean IOP 4 to 6 hours postoperatively was 47.09 mm Hg ± 7.92 (SD) (range 40 to 68 mm Hg). After decompression, the IOP dropped significantly to a mean of 4.73 ± 3.00 mm Hg at 0 minutes ( P<.001) and then increased progressively to 23.36 ± 10.80 mm Hg at 15 minutes ( P<.001), 33.82 ± 11.74 mm Hg at 30 minutes ( P=.005), 35.00 ± 6.53 mm Hg at 45 minutes ( P=.015), and 38.50 ± 2.51 mm Hg at 60 minutes ( P=.041). Conclusions Marked IOP spikes developed in eyes without glaucoma or ocular hypertension after uneventful phacoemulsification. Anterior chamber decompression immediately lowered IOP, but the effect was transient.