Rate of response to latanoprost or timolol in patients with ocular hypertension or glaucoma

PURPOSE: This study determined the rate of response to latanoprost compared with timolol in patients with glaucoma or ocular hypertension, whether some patients convert from non-responders to responders after more prolonged therapy, and whether this conversion represents a delayed response or random fluctuation. METHODS: In a previously described, multicenter, randomized, double-masked, parallel group study, patients received either 0.005% latanoprost once daily (n = 128) or 0.5% timolol twice daily (n = 140) for 6 months. Intraocular pressure (IOP) was assessed at baseline and at 0.5, 1.5, 3, 4.5, and 6 months of treatment at 8 am on all visits, and also at noon and 4 pm at baseline and 6 months. Rate of response based on diurnal measurement at 6 months compared with baseline was assessed using several criteria for response. Eyes with an IOP reduction of less than 15% compared with baseline at 8 am arbitrarily were classified as non-responders at each of the 5 visits during treatment. Consistency of non-responder classifications for individual eyes was assessed. RESULTS: Mean IOP reduction was greater (P < 0.001) in latanoprost-versus timolol-treated patients throughout the course of therapy. A greater rate of response occurred in patients treated with latanoprost, and differences in response rates between the 2 drugs increased as the definitions of response became more stringent. A greater percentage of non-responders at any single visit were classified as responders at all other visits with latanoprost in comparison with timolol. CONCLUSIONS: Latanoprost produces a greater rate of response compared with timolol. A higher percentage of non-responders to latanoprost compared with timolol on any individual visit are responders on all other visits. Likewise, a higher proportion of patients who do not initially respond will become responders with continued treatment with latanoprost compared with timolol.