Inter-visit intraocular pressure range: an alternative parameter for assessing intraocular pressure control in clinical trials

PURPOSE: To evaluate whether inter-visit intraocular pressure (IOP) range, which reflects extreme and potentially damaging IOP fluctuations, provides additional information on IOP control compared to mean IOP. DESIGN: Post hoc analysis of Xalatan/Lumigan/Travatan study data, a masked-evaluator, randomized, parallel-group comparison of 12-week efficacy of latanoprost, bimatoprost, and travoprost in open-angle glaucoma/ocular hypertension patients. METHODS: Pretreatment inter-visit IOP range defined as highest IOP minus lowest IOP at screening, safety check, and baseline (six measurements); posttreatment inter-visit IOP range defined as highest IOP minus lowest IOP at weeks two, six, and 12 or early termination (nine measurements). Ranges dichotomized as "high" (>6 mm Hg) vs "low" (< or =6 mm Hg). RESULTS: Included were 410 patients (latanoprost, 136; bimatoprost, 136; travoprost, 138). Each resulted in significant mean IOP range reductions during 12 weeks. Pretreatment inter-visit IOP range was associated with African-American race, male gender, and presence of visual field defect (P < .05 for all). Percentages with high pretreatment inter-visit IOP ranges were comparable across treatments (63% to 64%). High posttreatment inter-visit IOP range was seen in 21% (28/136), 28% (38/136), and 36% (50/138) of latanoprost, bimatoprost, and travoprost groups, respectively (P = .016, overall; P = .005, latanoprost vs travoprost). High posttreatment inter-visit IOP range was associated with African-American race, high pretreatment inter-visit IOP range, and treatment with travoprost vs latanoprost (P < .05 for all). CONCLUSIONS: Given that high inter-visit IOP range is associated with risk factors for glaucomatous damage and that such differences cannot be evaluated using mean IOPs, inter-visit IOP range may be another useful approach to assessing IOP control in clinical trials.