Effect of Brimonidine Tartrate Ophthalmic Solution 0.15% on Pupil Diameter in Normal Eyes

Abstract

Abstract: : Purpose: To evaluate the effect of brimonidine tartrate ophthalmic solution 0.15% (Alphagan P) on pupil diameter under different luminance conditions, and see if the 0.15% solution of brominidine tartrate possesses similar miotic properties as has been previously published for the 0.2% solution of brimonidine tartrate. Methods: Using the Colvard pupillometer, the pupil diameter in 15 eyes of 15 participants was measured under 3 different luminance conditions (scotopic, mesopic, photopic) while the participants fixated on a distant target 20 feet away. The luminance of the room was measured using the Minolta LS-110 Luminance Meter. One drop of 0.15% brimonidine tartrate ophthalmic solution was administered to each patient. Pupil diameter was measured using the same technique as stated above 30 minutes, 4 hours, and 6 hours after drop administration. Results: Under scoptopic conditions (luminance 0.0 cd/m²), 15 of 15 pupils (100%) and 13 of 15 pupils (86.7%) showed a decrease in diameter equal to or greater than 1 mm at 30 minutes and 4 hours, respectively (P<0.005). At 6 hours, the miotic effect of at least 1 mm or greater was still present in 9 of 15 participants (60%). Under mesopic conditions (luminance 0.18 cd/m²), 14 of 15 pupils (93.3%) and 11 of 15 pupils (73.3%) showed a decrease in pupil diameter greater than or equal to1 mm (P<0.005). By 6 hours, 6 of 15 pupils (40%) showed a decrease in diameter of at least 1mm or greater. Under photopic conditions (luminance 150.2 cd/m²), 11 of 15 pupils (73.3 %) and 13 of 15 pupils (86.7 %) showed a decrease in diameter equal to or greater than 1 mm at 30 minutes and 4 hours, respectively (P<0.005). By 6 hours, 10 of 15 eyes (66.7 %) still showed a decrease in pupil diameter of at least 1 mm or greater. Conclusions: Brimonidine tartrate 0.15 % ophthalmic solution showed a significant effect in decreasing pupil diameter under both scotopic and low light (mesopic) conditions which may be of use to postoperative refractive patients with night vision difficulties (halos, glare, etc). When compared to previous studies which used the 0.2% solution of brimonidine, the weaker 0.15 % concentration of brimonidine tartrate showed an equavalent ability to constrict the pupil. Also, the 0.15 % bromonidine tartrate ophthalmic solution showed a significant decrease in the pupil diameter under photopic conditions; a finding which was not observed in a prior study with 0.2% brimonidine tartrate ophthalmic solution.

Keywords: pupil • drug toxicity/drug effects • dark/light adaptation