Objective: To evaluate intraocular pressure (IOP) and ocular allergy after replacement of 1 of 2 adjunctive therapy regimens (fixed-combination dorzolamide/timolol or dorzolamide/timolol plus brimonidine) with fixed-combination brimonidine/timolol in glaucoma patients treated with ongoing prostaglandin analog (PGA) therapy.

Methods: This prospective, nonrandomized, open-label study involved patients on dorzolamide 2%/timolol 0.5% and a PGA who needed lower IOP and patients on brimonidine, dorzolamide 2%/timolol 0.5%, and a PGA who wanted to simplify their treatment regimens. After the baseline evaluation, patients were continued on the PGA and their other IOP-lowering medications were replaced with brimonidine 0.2%/timolol 0.5%. IOP was measured at baseline and months 1 and 3.

Results: In patients who replaced dorzolamide/timolol with brimonidine/timolol (n = 45), the mean (SD) IOP was 15.9 (1.4) mm Hg at baseline, 13.3 (0.9) mm Hg after 1 month (P < 0.001 vs. baseline), and 13.3 (1.0) mm Hg after 3 months (P < 0.001 vs. baseline). In patients who replaced both brimonidine and dorzolamide/timolol with brimonidine/timolol (n = 15), the mean (SD) IOP was 15.9 (5.2) mm Hg at baseline, 13.8 (1.8) mm Hg after 1 month (P = 0.053 vs. baseline), and 13.8 (1.4) mm Hg after 3 months (P = 0.079 vs. baseline). Allergy was reported in 5 patients previously treated with dorzolamide/timolol and 1 patient previously treated with brimonidine plus dorzolamide/timolol.

Conclusions: For patients on multiple-drug therapy including a PGA, replacement of dorzolamide/timolol with brimonidine/timolol may help achieve a lower IOP, while replacement of brimonidine plus dorzolamide/timolol with brimonidine/timolol may help achieve as low an IOP with fewer medications.