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March 1996

Around-the-Clock Intraocular Pressure Reduction With Once-Daily Application of Latanoprost by Itself or in Combination With Timolol

Arch Ophthalmol. 1996;114(3):268-273. doi:10.1001/archopht.1996.01100130264005

Objective:  To determine whether once-daily, in the morning, topical application of the new ocular hypotensive prostaglandin analogue, latanoprost, yields nocturnal intraocular pressure (IOP) reduction similar to its diurnal IOP reducing efficacy.

Study Design and Patients:  Placebo-controlled, randomized, and double-masked study on hospitalized patients with ocular hypertension or glaucoma. Patients in group 1 (n=9) were maintained on twice-daily applications of 0.5% timolol maleate. Patients in group 2 (n=10) terminated their timolol treatment 3 weeks before the beginning of the study. In both groups the test drug (0.005% latanoprost) and its vehicle (placebo) was applied by hospital staff every morning for 9 days.

Measurements:  After 4 days of ambulatory treatment, patients were hospitalized, and IOP values were obtained in the supine and sitting positions with a handheld electronic tonometer (Tono-Pen XL, Bio-Rad, Glendale, Calif) and a Goldmann's applanation tonometer, covering every 2-hour interval, around the clock, but not more than at four time points per day during a 5-day period.

Results:  The mean nocturnal IOPs (Goldmann's applanation tonometer) collected for 5 days were mean±SEM 17.9±0.6 vs 20.2±0.6 mm Hg and 16.8±0.3 vs 20.6±0.5 mm Hg for the study vs the control eyes in group 1 and group 2, respectively. These nocturnal IOP reductions were statistically significant (P<.001, two-tailed paired Student's t test). The differences between diurnal and nocturnal IOP reductions (handheld electronic or Goldmann's applanation tonometer) were minimal (<0.3 mm Hg) and statistically not significant (P>.31, two-tailed paired Student's t test).

Conclusion:  Once-daily latanoprost treatment provides uniform circadian (around-the-clock) IOP reduction by itself, or in combination with timolol.