Acute veru chronic effect of brimonidine on aqueou humor dynamic in ocular hypertenive patient Original Reearch Article

PURPOE: To report the acute v chronic effect of brimonidine, a elective α2-adrenergic receptor agonit, on aqueou humor dynamic in ocular hypertenive patient. METHOD: Brimonidine 0.2% wa given topically twice daily for 29 day to one eye each of 28 ocular hypertenive volunteer in a randomized double-maked tudy. The fellow eye wa imilarly treated with vehicle. Aqueou flow (Fa) and outflow facility (Cfl) were determined with fluorophotometry. Intraocular preure, outflow facility (Cton), and epicleral venou preure (Pev) were meaured with pneumatonometry, tonography, and venomanometry, repectively. Uveocleral outflow (Fu) wa calculated from intraocular preure, Fa, Pev, and Cfl value. All meaurement were taken on baeline day, day 8, and day 29 of treatment. Intraocular preure and Fa only were meaured after intillation of 1 drop of brimonidine on day 1. REULT: When meaured 3 hour after intillation on day 1, 8, and 29 of treatment, brimonidine ignificantly (P < .001) reduced intraocular preure by at leat 5.0 ± 0.7 mm Hg (mean ± EM) compared with baeline day, and by 2.7 ± 0.5 mm Hg compared with the vehicle-treated contralateral control eye. The greatet decreae (6.0 ± 0.6 mm Hg) wa oberved at 3 hour after the firt drop. Aqueou flow wa reduced by 29% (P < .001) after the firt application but wa not ignificantly different from baeline when meaured at day 29 of treatment. Uveocleral outflow wa increaed 60% at day 8 (P < .06) and day 29 (P < .05) compared with baeline. There wa no ignificant difference in outflow facility or epicleral venou preure at day 8 or day 29 of treatment. CONCLUION: The brimonidine-induced reduction in intraocular preure in human i aociated initially with a decreae in aqueou flow, and after chronic treatment with an increae in uveocleral outflow.