Effects of Timolol and Dorzolamide on Ocular Blood Flow in Patients with Open Angle Glaucoma and Ocular Hypertension

Abstract

Abstract: : Purpose: There is evidence from previous studies that topical dorzolamide may improve ocular blood flow in glaucoma. However, most of the currently available data arise from studies with only a small number of patients included. We set out to investigate the effects of timolol versus dorzolamide in a larger number of primary open angle glaucoma (POAG) and ocular hypertensive (OHT) patients. Methods: In 140 patients with either POAG or OHT the effect of a 6 months treatment period of dorzolamide versus timolol on ocular hemodynamic parameters was studied. The design of the trial was randomized (1:1), double-masked in two parallel groups. Blood flow in the rim (RimBF) and the cup (CupBF) of the optic nerve head were measured with scanning laser Doppler flowmetry. Pulsatile choroidal blood flow was assessed with laser interferometric measurement of fundus pulsation amplitude (FPA). Results: All outcome parameters were comparable between groups at baseline. Both, dorzolamide and timolol reduced intraocular pressure to a comparable degree. However, dorzolamide, but not timolol increased RimBF (8.5±12.0%; p=0.0002 versus timolol), CupBF (13.5±18.2%; p=0.0002 versus timolol) and FPA (8.9±9.2%; p<0.0001 versus timolol). Conclusions: Our data indicate that dorzolamide increases optic nerve head and choroidal blood flow in patients with POAG or OHT. Whether this means that dorzolamide is superior to timolol in preserving the visual field in glaucoma patients remains to be established.

Keywords: clinical (human) or epidemiologic studies: tre • blood supply • pharmacology