Purpose: To compare the intraocular pressure-lowering effect of latanoprost with that of dorzolamide when added to timolol.
Patients and methods: This randomized, open-label study with two parallel groups was conducted in five centers in Greece. The study enrolled 148 patients with inadequately controlled open-angle or pseudoexfoliation glaucoma (intraocular pressure of at least 22 mm Hg) or ocular hypertension (intraocular pressure of at least 27 mm Hg) who were receiving monotherapy with a beta-blocker or dual therapy in which one of the agents was a beta-blocker. The patients were switched to timolol 0.5% twice daily for 2 to 4 weeks (run-in period) before the start of the study (baseline). At baseline, the patients were randomized to receive latanoprost 0.005% once daily or dorzolamide 2% twice daily as add-on therapy to timolol. The intraocular pressure was recorded at 9:30 AM, 12:30 PM, and 3:30 PM at baseline and at 3 months. Safety was followed throughout the study.
Results: The diurnal intraocular pressure reduction was significant in both groups (P < 0.001). The mean intraocular pressure reduction from baseline was 32% for the latanoprost plus timolol group and 20% for the dorzolamide plus timolol group. The least square estimate of the mean diurnal intraocular pressure reduction after 3 months was -7.06 mm Hg in the latanoprost plus timolol group and -4.44 mm Hg in the dorzolamide plus timolol group (P < 0.001). Drugs administered in both treatment groups were well tolerated.
Conclusion: This study clearly showed that the additive diurnal intraocular pressure-lowering effect of latanoprost is superior to that of dorzolamide in patients treated with timolol.