Comparison of Intraocular Pressure Lowering Effect of Once Daily Morning vs Evening Dosing of Latanoprost/Timolol Maleate Combination

Purpose To compare intraocular pressure (IOP) reduction profiles of latanoprost-timolol maleate fixed combination (LTFC) administered in the morning or evening in primary open angle glaucoma (POAG). Methods A prospective, randomized study including 60 eyes of 30 patients with POAG was carried out. Patients were randomized to treatment with LTFC at 8 PM (Group 1) or at 8 AM (Group 2). After therapy of 4 weeks, IOP was measured at 2 AM, 6 AM, 10 AM, 2 PM, 6 PM, and 10 PM and compared with baseline values and latanoprost therapy alone. Results Mean diurnal baseline IOPs and IOPs after treatment with latanoprost and LTFC were 23.6±2.6, 16.7±2.3, and 15.5±2.2 mmHg in Group 1 and 23.1±2.6, 16.9±2.4, and 15.7±2.4 mmHg in Group 2. LTFC lowered IOP more than latanoprost at all time points in both groups (p<0.001) (except 6 AM in Group 2). The mean IOP range after LTFC therapy was lower than the baseline in Group 1 whereas it was not different in Group 2. IOP at 10 AM was significantly higher than the other time points at baseline measurements in both groups (p<0.01) but after treatment there was no difference (p>0.05). According to IOP reduction from baseline, there was a statistically significant difference between groups in favor of Group 1 at 6 AM, 10 AM, and mean diurnal measurement (p<0.01). Conclusions Both morning and evening dosing of LTFC were effective in lowering diurnal IOP in patients with POAG. However, evening dosing of LTFC seemed to be more effective in controlling IOP especially in the morning and avoiding the fluctuations with lower range of IOP