Background: The purpose of this prospective study was to investigate the intraocular pressure (IOP)-lowering effect and safety of latanoprost 0.005% + timolol maleate 0.5% fixed combination eyedrops, now available in Japan.

Methods: Thirty-one patients diagnosed with primary open-angle glaucoma who had an insufficient intraocular pressure (IOP) decrease with latanoprost 0.005% eyedrop monotherapy were enrolled. The latanoprost 0.005% eyedrops were discontinued, and administration of latanoprost 0.005%/timolol maleate 0.5% fixed combination eyedrops was initiated without any washout period. IOP was compared before and at months 1, 3, and 6 after the switch. The incidence of adverse reactions was investigated at every follow-up visit.

Results: Mean IOP was 17.3 ± 2.7 mmHg before the switch, 15.5 ± 2.6 mmHg one month after the switch, 14.9 ± 2.4 mmHg 3 months after the switch, and 15.1 ± 2.2 mmHg 6 months after the switch, indicating that IOP decreased significantly after the change. The IOP reduction rate was 9.9% ± 11.5% after one month, 13.1% ± 10.9% after 3 months, and 11.2% ± 11.8% after 6 months. Two patients (6.5%) discontinued therapy due to adverse reactions (one case each of itchiness and bradycardia).

Conclusions: When latanoprost 0.005% eyedrop monotherapy was replaced by latanoprost 0.005% + timolol maleate 0.5% fixed combination eyedrops, IOP decreased significantly without increasing the frequency of administration, and safety was satisfactory.