Purpose: To compare the effects of topical Betablockers on ocular hemodynamics and especially optic nerve head blood flow.
Methods: 12 primary open angle glaucoma patients (57 y) were included in the study. In a randomized, double masked, crossover design all patients were treated for 4 weeks each with betaxolol (BX), metipranolol 0,3 % (ML) and timolol 0.5 % (TL). At baseline IOP, pulsatile ocular blood flow (POBF), trabecular resistance as measured by tonography and capillary optic nerve head blood flow were examined. ONH-perfusion was measured by scanning laser flowmetry and ocular pulse amplitudes by using the OBF-system (UK)Ltd.. All measurements were repeated after 29 days of therapy.
Results: IOP showed the expected drop under each treatment (BL x=-6.3 mmHg, ML x=-6.9 mmHg, TL x =-6.9 mmHg), ONH blood flow increased in timolol (delta x=178 AU) and metipranolol (delta x=51 AU) subjects and decreased in the betaxolol group ( x=-123 AU). Pulsatile ocular blood flow increased in the timolol group (x=64µl/min) and decreased in the other two (BX=-62 µl/min; ML=-116 µl/min). Systolic and diastolic blood pressure as well as heart rate decreased in all groups examined whereas there was found no difference in trabecular resistance.
Conclusions: This effect seems therefore not only due to the greater IOP reduction under these medications. 1University Eye Clinic Hamburg, Germany 2University Eye Clinic San Diego, U.S.