Assessing the efficacy of latanoprost vs timolol using an alternate efficacy parameter: the intervisit intraocular pressure range.

Purpose: To compare latanoprost and timolol with regard to changes in the intervisit intraocular pressure (IOP) range, a measure of long-term IOP fluctuation.

Design: Post hoc analysis of three 6-month, multicenter, randomized (1:1), double-masked registration trials of latanoprost (n = 313) vs timolol (n = 318).

Methods: Analyses included patients with glaucoma or ocular hypertension who instilled latanoprost once daily in the evening and vehicle in the morning and those instilling timolol twice daily. Pretreatment intervisit IOP range: highest IOP minus lowest IOP of 4 measurements obtained at screening and baseline. Posttreatment intervisit IOP range: highest IOP minus lowest IOP of 4 measurements obtained at weeks 18 and 26. Ranges were dichotomized to high (> 6 mm Hg) and low (< or = 6 mm Hg).

Results: Both treatments resulted in significant reductions in mean intervisit IOP range during 26 weeks. Pretreatment, comparable proportions of patients treated with latanoprost and timolol had high intervisit IOP ranges (22% [70/313] and 23% [72/318], respectively; P = .934). After treatment, 6% (19/313) and 11% (35/318) of patients in the latanoprost and timolol groups, respectively, had high intervisit IOP ranges (P = .026). Significant risk factors for high posttreatment intervisit range (multivariate logistic regression) were high pretreatment intervisit IOP range, treatment with timolol, Black race, longer time since diagnosis, and higher mean pretreatment IOP.

Conclusions: Compared with timolol, treatment with latanoprost results in significantly fewer patients with a high IOP fluctuation. The impact of reducing high IOP fluctuation on progressive glaucomatous damage deserves further investigation in prospective studies.