Abstract
Purpose. To evaluate the effects of topical carteolol or timolol on tissue circulation in the iris and posterior choroid. Methods. After a topical instillation of 20 µl of 2% carteolol, 0.5% timolol, or physiological saline (for control) into one eye, and physiological saline into the other eye of pento-barbital-anesthetized Dutch pigmented rabbits, normalized blur value; a quantitative index of tissue blood velocity in the iris (NB iris) and posterior choroid (NB cho) was obtained using the laser-speckle method. Intraocular pressure (IOP), blood pressure and pulse rate were serially monitored for 2 hours after instillation. Using separate groups of rabbits, NB iris and IOP were measured before and after 20-day twice-daily unilateral treatment of carteolol or timolol. Results. After a single instillation of carteolol, NB iris was significantly greater only in the treated eyes than control eyes (P = 0.0050, repeated measures two-way ANOVA), while NB cho showed no significant change. IOP in the treated eyes significantly reduced (P = 0.0005). Bilateral reductions of tissue vascular resistance in the iris were found after carteolol instillation (P = 0.0183 ~ 0.0322). After timolol instillation, serial changes in NB iris and NB cho in the treated eyes were significantly different from those in control eyes (P = 0.0129, 0.0031), while there were no significant differences at any of time points (Mann-Whitney test); IOP in both eyes was significantly reduced (P = 0.0096 ~ 0.0005); tissue vascular resistance in the iris and posterior choroid showed no significant changes. After 20-day treatment, NB iris in the both eyes of carteolol-treated rabbits significantly increased from the baseline (P = 0.0280, 0.0425, Wilcoxon signed rank test) and NB iris in timolol-treated eyes significantly decreased (P = 0.0280). Conclusions. A single instillation of topical carteolol significantly increased the iris tissue blood velocity in the treated eye and reduced the tissue vascular resistance in both eyes. Topical timolol tended to decrease tissue blood velocity in the iris and choroid of the treated eye, but showed no significant effects on tissue vascular resistance in the both tissues.
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