A comparison of the effects of 0.005% latanoprost and fixed combination dorzolamide/timolol on retrobulbar haemodynamics in previously untreated glaucoma patients

Abstract

Objective: To assess the effects of dorzolamide/timolol fixed combination (DTFC) and latanoprost 0.005% on the retrobulbar haemodynamics and intraocular pressure (IOP) of open-angle glaucoma patients.

Methods: 22 consecutive subjects with newly diagnosed, open-angle glaucoma were included in this prospective, examiner masked, randomized, crossover study. The patients were randomized into two different arms. Peak systolic velocity (PSV), end-diastolic velocity (EDV), Pourcelot's resistance index (RI) and intraocular pressure (IOP) were determined at baseline and after 1 month of medical treatment with DTFC or latanoprost 0.005% in both groups. A 4-week washout period, without medical treatment, between study arms was carried out. Primary efficacy variables were the PSV, EDV and RI in the ophthalmic artery (OA) and short posterior ciliary artery (SPCA) and intraocular pressure (IOP). Inter- and intra-group comparisons were performed with a one-way ANOVA test and two-tailed paired Student's t-test respectively.

Results: Intraocular pressure (IOP) and colour Doppler imaging (CDI) measurements were similar at baseline. Compared to baseline and washout measurements, only the fixed combination dorzolamide/timolol significantly increased the EDV in the OA and in the SPCA, p = 0.00012 and p = 0.00012, respectively and decreased the resistance index in the ophthalmic and short posterior ciliary arteries, p = 0.00011 and p = 0.00031, respectively. There were no statistically significant differences in the IOP lowering effect of either treatment.

Conclusion: Over a treatment period of 1 month, only the fixed combination dorzolamide/timolol seems to have a vascular effect on retrobulbar vessels. Further research is necessary to confirm these results.