Abstract
Abstract: :
Purpose:Betablockers are a common treatment of glaucoma because of their intraocular pressure lowering effect. Little, however, is known about their effect on ocular blood flow. This study evaluates the influence of different betablockers on ocular hemodynamics and optic nerve head blood flow in glaucoma patients. Methods:30 patients (12 male, 18 female) with primary open-angle glaucoma between 39 and 74 years of age were included in the study. All patients were treated for 4 weeks each with betaxolol (BX), metipranolol 0,3% (ML) and timolol 0,5% (TL) in a randomized, double masked, crossover design. At baseline intraocular pressure, pulsatile ocular blood flow, capillary optic nerve head blood flow and systemic parameters like blood pressure and heart rate were examined. ONH-blood velocity, volume and flow were measured by means of scanning laser Doppler flowmetry (Heidelberg Retina Flowmeter). Pulsatile ocular blood flow, representing primarily chorioidal hemodynamics, was recorded by using the OBF-system. After 29 days of treatment all measurements were repeated. Results:Intraocular pressure showed the expected drop in all 3 substances (betaxolol x = -6,1 mmHg, metipranolol x = -6,3 mmHg, timolol x = -5,7 mmHg). Optic nerve head blood flow increased in metipranolol (delta x = 79 AU) and timolol (delta x = 140 AU) and decreased in subjects treated with betaxolol (delta x = -15 AU). Pulsatile ocular blood flow increased in metipranolol (x = 61 µl/min) and decreased in the other two groups (BX = -11 µl/min, TL = -43,7 µl/min). Systolic and diastolic blood pressure decreased in betaxolol and timolol whereas in metipranolol there was found no significant change. Conclusion:Although unselective betablocking agents are expected to have a lowering effect on ocular perfusion parameters, the results of our study showed the opposite : timolol and metipranolol led to an increase of ocular nerve head blood flow in comparison to the effect of betaxolol in patients with primary open-angle glaucoma.
Keywords: 499 optic flow • 514 pharmacology