['To verify the influence of a non-steroidal anti-inflammatory drug (NSAID), ketorolac (topical and oral) on the intraocular pressure reduction induced by 0.005% latanoprost topical administration, both in patients affected by primary open-angle glaucoma and in healthy controls.', 'Two groups of subjects were enrolled for this randomized, prospective, masked clinical study: 16 glaucomatous patients well controlled with 0.005% latanoprost eyedrops (group I) and 16 healthy adult volunteers (group II). Group I subjects were treated at one-week intervals with 10 mg of oral ketorolac, oral placebo, topical ketorolac, and topical placebo, respectively; for each administration modality, the switch between drug and placebo was performed in a randomized, crossover, double-blind fashion. Group II subjects followed the same protocol, with the topical once-daily 0.005% latanoprost treatment starting three days prior to the ketorolac/placebo administration. Intraocular pressure (IOP) was investigated in both groups on the day of oral/topical administration of ketorolac or placebo at baseline (8:00 AM) and at the following intervals: 1, 2, 4, 8, 12, and 24 hours.', 'No significant IOP changes after oral and topical placebo administration were observed in either group. In contrast, when the subjects received ketorolac (either oral or topical), a marked decrease in IOP was recorded, with a noticeable fall at the first hour after the NSAID administration (p = 0.01), which remained still significant 8 hours later (p < 0.05).'] Does topical and oral ketorolac administration increase the intraocular pressure-lowering effect of latanoprost?