Purpose: To compare the effects of latanoprost/timolol (LTFC) versus dorzolamide/timolol (DTFC) fixed combinations on intraocular pressure (IOP), visual function, and retrobulbar blood flow in patients with open-angle glaucoma (OAG).
Methods: This was a prospective, randomized, double masked, parallel study on 30 patients with OAG. All patients received 4 weeks of timolol treatment prior to randomization to LTFC or DTFC treatment. Measurements after randomization were taken at 1, 6, and 12 months, including arterial blood pressure; IOP; color Doppler imaging of the ophthalmic artery (OA), central retinal artery, and short posterior ciliary artery (SPCA); scanning laser polarimetry; Humphrey visual field examination; and adverse events.
Results: IOP decreased by 5.0 mmHg in the DTFC cohort (p<0.000) and 5.44 mmHg in the LTFC cohort (p=0.0001) after 12 months of treatment. No statistically significant differences in visual field or nerve fiber layer thickness were observed between the treatment groups during 12 months of therapy. Mean increase over 1 year of treatment in ocular perfusion and diastolic perfusion pressures were 10.46% and 10.67% in the DTFC group and 7.47% and 5.61% in the LTFC group, respectively. OA resistive index (RI) and SPCA RI were significantly different at the 12 months visit between the two treatment groups (p=0.05 and p=0.000, respectively): DTFC treatment showed decrease in the RI.
Conclusions: One year of treatment with LTFC or DTFC resulted in similar IOP lowering effects as well as stable visual function and structure. The DTFC group showed lower vascular resistance in retrobulbar vessels compared to the LTFC group.