EFFECTS OF DORZOLAMIDE HYDROCHLORIDE 2-PERCENT ON THE RETINAL CIRCULATION

Purpose: To study the effect of a single dose of topical dorzolamide h ydrochloride 2%, a carbonic anhydrase inhibitor, on the retinal circul ation of normal subjects. Methods: Measurements of the effect of dorzo lamide hydrochloride were performed in 20 normal subjects using bidire ctional laser Doppler velocimetry and monochromatic fundus photography . In a double-masked randomized design, one eye received one drop of d orzolamide hydrochloride 2% and the other eye one drop of placebo. Ves sel diameter, maximum erythrocyte velocity and volumetric blood flow r ate were measured in a main temporal vein of each eye before the drops , and then, 2 h later. Results: Following treatment, intraocular press ure decreased by 12% in the dorzolamide-treated eye (p = 0.0004, paire d Student's t-test) and by 4% in the placebo-treated eye, p = 0.04). N o significant changes in venous diameter, maximum erythrocyte velocity , and volumetric blood flow rate were observed in the dorzolamide-trea ted eyes (0.6%, 2.6% and 1.4%, respectively) or the placebo-treated ey es (1%, 3.7% and 1.6%, respectively). Conclusions: A single drop of do rzolamide hydrochloride does not cause any significant change in any o f the hemodynamic parameters measured. With the variability of our mea surements,,ve have about 89% power to detect average 10% change in vol umetric blood flow rate if significance testing is performed at p = 0. 05 level.