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Comparison of Different Topical Beta-blockers with Regard to their Effect on Ocular Hemodynamics and the Optic Nerve Head Blood Flow in Glaucoma Patients
Köller U. A., Müller M. F., Böhm A. G., Mollenhauer K., Pillunat L. E.,
Universitätsklinikum Carl Gustav Carus, Klinik und Poliklinik für Augenheilkunde (Dresden)
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.
Method: 30 patients (12 male, 18 female; average age 56,6 years) with primary open-angle glaucoma 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 heartrate and blood pressure were examined. Optic nerve head blood flow was 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.
Conclusions: 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.