A comparative analysis of the effects of the fixed combination of timolol and dorzolamide versus latanoprost plus timolol on ocular hemodynamics and visual function in patients with primary open-angle glaucoma

Aims: The aim of this study was to assess the effects of fixed combination of timolol and dorzolamide and latanoprost plus timolol on retinal, choroidal, and retrobulbar hemodynamics and visual function in primary open-angle glaucoma (OAG) subjects. Methods: Sixteen (16) OAG patients (age, 63.5.+/- 10.8 years; 9 male) were evaluated in a randomized, crossover, double-blind study design after 4 weeks of treatment of latanoprost with timolol and fixed combination of timolol and dorzolamide. After randomization, 9 right eyes and 7 left eyes were included in the hemodynamic portion of the study. Measurements included: adverse events check, visual acuity, contrast sensitivity, blood pressure, heart rate, intraocular pressure (IOP), and fundus examination. Ocular blood flow was assessed using confocal scanning laser Doppler flowmetry, color Doppler imaging, and scanning laser ophthalmoscopy. Results: Both therapies were effective at lowering IOP, whereas there was no statistically significant difference between latanoprost plus timolol and the fixed combination of timolol and dorzolamide (13.9% and 12.2% reduction, respectively; P = 0.5533). Fixed combination of timolol and dorzolamide significantly increased central retinal artery end diastolic blood flow velocity W = 0.0168) and lowered resistance to flow W = 0.0279). Temporal posterior ciliary artery peak systolic and end diastolic velocities were significantly increased with the fixed combination of timolol and dorzolamide W = 0.0125 and 0.0238, respectively). Latanoprost plus timolol had no significant effects on ocular blood flow during 4 weeks of treatment. There were no statistically significant differences in adverse events, blood pressure, heart rate, visual acuity, contrast sensitivity scanning laser ophthalmoscopy, or Heidelberg Retinal Flowmeter for any treatment period. Conclusions: Fixed combination of timolol and dorzolamide therapy might increase blood flow in OAG patients while attaining a similar IOP reduction compared to latanoprost plus timolol. Visual function, however, was not different in this short-term comparison between the two treatments.