[Effects of beta-adrenergic blockers on retinal circulation]

We evaluated the effects of 0.5% betaxolol hydrochloride and 0.5% timolol maleate on retinal blood flow. We measured the diameter of the retinal artery (Da) and vein (Dv), and retinal venous blood flow rate (V) in 8 healthy young volunteers by laser speckle velocimetry before and after the application of betaxolol or timolol topically to both eyes daily for one week. There were no any significant changes. Da before and after the application of betaxolol was 114.2 +/- 6.3 (mean +/- standard deviation) microns and 115.6 +/- 6.7 microns and before and after the application of timolol, 117.5 +/- 12.7 microns and 101.3 +/- 9.5 microns. Dv before and after the application of betaxolol was 149.5 +/- 11.1 microns and 148.4 +/- 13.3 microns, and before and after the application of timolol 148.5 +/- 9.2 microns and 146.2 +/- 10.3 microns. V before and after the application of timolol was 12.3 +/- 2.6 mm/s and 12.6 +/- 2.4 mm/s, and before and after the application of betaxolol, 11.6 +/- 1.5 mm/s and 11.4 +/- 2.1 mm/s. Thus one-week application of the beta-blockers, betaxolol and timolol did not change the retinal arterial or venous blood flow.