A Comparative Study of the Effects of Timolol and Latanoprost on Blood Flow Velocity of the Retrobulbar Vessels

To examine the effects of topical timolol and latanoprost on retrobulbar vessel blood velocity in patients with glaucoma or ocular hypertension. Nine patients with primary open-angle glaucoma and six patients with ocular hypertension were enrolled for this study. All patients were treated topically with 0.5% timolol or 0.005% latanoprost, using a double-masked crossover design with a 3-week washout before administration of each drug. Each patient had a baseline color Doppler imaging ultrasound of the central retinal artery, short posterior ciliary arteries, and ophthalmic artery and two other ultrasound examinations during the 1-week treatment with each drug, performed 12 hours after the first dose of the drug and 12 hours after the last dose, 7 days later. Both topical timolol and topical latanoprost significantly reduced the intraocular pressure. The only significant change observed in the retrobulbar blood velocity with timolol was a reduction of end diastolic velocity in the ophthalmic artery 12 hours after the first dose, accompanied by a trend toward a decrease in the peak systolic velocity and an increase in the resistance index in the same vessel. No change in blood velocity was observed with latanoprost. Topical timolol and latanoprost significantly reduced the intraocular pressure in ocular hypertensive and glaucoma patients without creating substantial hemodynamic changes in the retrobulbar vessels.