Purpose: To investigate the effect of timolol-dorzolamide and timolol-pilocarpine fixed combinations on retrobulbar vessel blood flow.
Design: Prospective, randomized, masked, crossover clinical trial.
Methods: Sixteen patients with primary open angle glaucoma, treated with timolol 0.5%, received timolol 0.5%-dorzolamide 2% and timolol 0.5%-pilocarpine 2% for four weeks each. Heart rate, blood pressure, intraocular pressure (IOP), and peak systolic (PSV) and end diastolic velocities (EDV) in ophthalmic, central retinal, and short posterior ciliary arteries were measured before and after each treatment, and resistivity index was calculated.
Results: The IOP was reduced (P < .01) by timolol-dorzolamide and, more effectively, timolol-pilocarpine combinations. In central retinal artery, the end diastolic velocity was increased by the timolol-dorzolamide combination (P < .01), resulting in higher end diastolic velocity and lower resistivity index values (both P < .01) compared with the timolol-pilocarpine combination.
Conclusions: The timolol-dorzolamide combination increases the end diastolic velocity in central retinal artery, despite a lower intraocular pressure decrease, suggesting an effect on retinal circulation.