A comparison of the effects of dorzolamide/timolol fixed combination versus latanoprost on intraocular pressure and pulsatile ocular blood flow in primary open-angle glaucoma patients

Purpose: To evaluate the effects of dorzolamide/timolol fixed combination (D/T) compared to latanoprost on intraocular pressure (IOP) and pulsatile ocular blood flow (POBF) in primary open-angle glaucoma (POAG) patients. Methods: Thirty patients with POAG were randomized in an open-label, cross-over study. Intraocular pressure reduction was achieved by 4 weeks medical therapy with D/T twice daily or latanoprost 0.005% dosed once in the evening. During a 4-week run-in and a 4-week wash-out period between study arms, patients ceased use of all other glaucoma medications and used timolol maleate 0.5% twice daily. Primary efficacy variables were IOP and POBF. Results: There was no difference in baseline IOP and POBF parameters between the two study arms. Both D/T and latanoprost statistically significantly reduced IOP by 4.6 mmHg (p<0.0001) and 3.75 mmHg (p< 0.0001) and increased POBF by 2.048 μl/second (p = 0.0030) and 2.147μl/second (p = 0.0009), respectively. Repeated measures ANOVA detected significant changes in POBF with treatment (p = 0.0361). Dorzolamide/timolol fixed combination statistically significantly increased pulse volume by 0.767μl (p = 0.0087), while latanoprost therapy had no significant effect (p = 0.2407). Conclusions: Both drugs had similar effects in terms of IOP reduction. Dorzolamide/timolol significantly increased pulse volume while latanoprost had no effect. Further studies are necessary to establish whether the enhancement of choroidal blood flow can prevent glaucoma progression.