Effect of topical carteolol on iridial circulation in pigmented rabbit eyes

The effect of a single instillation of topical carteolol on iridial tissue circulation of pigmented rabbits was studied. The blood flow rate and a quantitative index of tissue blood velocity (NBiris) were measured simultaneously, using the microsphere technique and the laser speckle method, before and 2 hours after the instillation of 20 microliters of 2% carteolol or the vehicle. Consecutive changes of intraocular pressure and NBiris were also studied at 30-minute intervals for 2.5 hours after a single instillation of 2% carteolol in one eye and the vehicle in the contralateral eye. To provide a control, intraocular pressure and NBiris were measured according to the same schedule after the vehicle instillation in both eyes. Two hours after carteolol instillation, iridial blood flow rate and NBiris significantly increased to 127 +/- 8% and 122 +/- 9% (mean +/- SEM, n = 8) of the baseline. Unilateral instillation of carteolol significantly reduced intraocular pressure by about 9 mm Hg in both the carteolol- and vehicle-treated eyes (P < 0.001, analysis of variance); and NBiris was significantly increased by about 20% in both eyes (P < 0.001, analysis of variance), compared with control eyes.