Effect of 6-week washout period on intraocular pressure following chronic prostaglandin analogue treatment: a randomized controlled trial.

OBJECTIVE:To evaluate the effect of a 6-week washout period on intraocular pressure (IOP) following long-term monotherapy prostaglandin use. DESIGN:Prospective, randomized, controlled, single-centre, single-blinded, parallel-group clinical study. PARTICIPANTS:Subjects aged >18 years diagnosed with open-angle glaucoma or open-angle glaucoma suspects based on elevated IOP in one or both eyes, using monotherapy topical latanoprost, bimatoprost, or travoprost once daily. METHODS:Subjects were prospectively randomized to continue prostaglandin analogue (PGA) monotherapy (control group) or discontinue PGA monotherapy (washout group) for 42 days. IOP was measured at day 0 (day of randomization), 7, 21, and 42. MAIN OUTCOME MEASURE:Mean IOP (mm Hg) ± standard deviation. RESULTS:154 eyes (87 participants) completed the study, with 69 eyes (39 participants) in the control group and 85 eyes (48 participants) in the washout group. In the control group, day 0 IOP (14.64 ± 2.68 mm Hg) did not significantly differ from IOP at days 7 (14.25 ± 3.01 mm Hg), 21 (14.57 ± 2.61 mm Hg), and 42 (14.78 ± 2.30 mm Hg) (all p > 0.30). In the washout group, mean IOP values at days 7 (16.19 ± 3.80 mm Hg), 21 (17.28 ± 3.55 mm Hg), and 42 (17.84 ± 3.31 mm Hg) were significantly greater than those at day 0 (14.48 ± 1.94 mm Hg) and day-matched control group values (all p < 0.002). In the washout group, 24.7% of eyes had a day 42 IOP ≥21 mm Hg. No eyes in the control group had a day 42 IOP ≥21 mm Hg. CONCLUSIONS:Six weeks of PGA washout after long-term monotherapy resulted in a small but statistically significant IOP increase. Majority of washout group participants maintained an IOP lower than 21 mm Hg after the 6-week washout duration. (https://clinicaltrials.gov/ identifier, NCT03534882).