The effect of brimonidine tartrate on retinal blood flow in patient with ocular hypertenion

PURPOE: To tudy the effect of topical brimonidine tartrate 0.2%, an α2-agonit ocular hypotenive drug, on retinal capillary blood flow in patient with ocular hypertenion. METHOD: The tudy wa a double-maked, randomized, placebo-controlled trial et in a tertiary eye center. Ocular hypertenive patient with repeatable intraocular preure greater than 21 mm Hg and normal viual field and optic dik were conecutively recruited. After an eye examination, baeline retinal blood flow meaurement were made with confocal canning laer Doppler flowmetry in one tudy eye. Patient were then randomly aigned to receive either brimonidine or placebo (aline) twice daily for 8 week. Blood flow and intraocular preure meaurement were then repeated after 4 and 8 week. REULT: eventeen patient were randomly aigned to receive brimonidine, and 14 received placebo. One patient in each group failed to complete the tudy. The mean group difference in baeline age and intraocular preure were not tatitically ignificant (59.23 [±10.24] and 52.23 [±16.46] year, repectively, and 24.84 [±2.08] and 24.56 [±2.85] mm Hg, repectively). Brimonidine reduced intraocular preure by 17.90% and 16.17% at 4 and 8 week, repectively, with a ignificant difference in treatment effect compared with the placebo group (P< .007). The group difference in treatment effect in any of the three hemodynamic parameter velocity, volume, and flow wa within 8% and not ignificantly different at 4 or 8 week (P> .360). Baed on a type I error of 0.05, our tudy had a power greater than or equal to 75% to detect group difference in treatment effect of greater than or equal to 15% to 20%. CONCLUION: Brimonidine reduce intraocular preure without altering retinal capillary blood flow in patient with ocular hypertenion.