Beneficial effects of fixed combination of timolol and dorzolamide on optic nerve head blood circulation

Ikuyo Ohguro

Purpose: The purpose of the present study was to investigate the effects of fixed combination of timolol and dorzolamide on blood circulation of optic discs in healthy volunteers.

Methods: Fifteen healthy volunteers (4 male and 11 female, 20±0.9 years ) were included in this study. One drop of either 0.5% timolol, 1% dorzolamide or fixed combination of 0.5% timolol and 1% dorzolamide, and saline were administrated to their right and left eyes, respectively. Systemic blood pressures, pulse rates, intraocular pressures (IOPs), and blood circulation by a laser speckle flow meter at the optic nerve head (ONH) were measured before, and 1.5 and 6 hours after the eye drop.

Results: Upon administration of timolol and fixed combination of timolol and dorzolamide, minimum changes were observed in systemic blood pressures and pulse rates. In all of the eye drops, significant decrease of IOPs was observed during the 6 hours. However, the blood flows of ONH were significantly increased only in the fixed combination of timolol and dorzolamide as compared with their saline-treated eye, but not in timolol or dorzolamide (P=0.05, Mann-Whitney U-test).

Conclusion: Present our results suggest that fixed combination of timolol and dorzolamide might be expected to cause increase of the ocular blood circulation around the ONH presumably by a synergistic effect of timolol and dorzolamide, in addition to their IOP reduction effects.