“…42,43 There have been several reports suggesting the beneficial effects of topical betaxolol on the retinal, optic nerve head or retrobulbar circulation in humans, [44][45][46][47] and Yu et al found that betaxolol at concentrations higher than 10 Ϫ12 M caused dilation of endothelin-1 preconstricted, isolated, and perfused human retinal arterioles. 48 Taken together with these previous findings, the possible relation of the vascular effects of betaxolol to the present findings cannot be ruled out. Several in vitro studies have demonstrated the neuroprotective effects of betaxolol at relatively high concentrations.…”