Miotic effect of brimonidine tartrate 0.15% ophthalmic solution in normal eyes

Purpose: To evaluate the effect of brimonidine tartrate 0.15% ophthalmic solution (Alphagan^® P) on pupil diameter in eyes of healthy adults under different luminance conditions. Setting: Center for Refractive Surgery, Ophthalmology Service, Department of Surgery, Walter Reed Army Medical Center, Washington, DC, USA. Methods: Using a Colvard pupillometer, the pupil diameter was measured in 15 eyes of 15 healthy adults under 3 luminance conditions (scotopic, mesopic, photopic). The luminance of the room was measured using the Minolta LS-110 Luminance Meter. Pupil diameter was remeasured using the same technique 30 minutes, 4 hours, and 6 hours after administration of 1 drop of brimonidine tartrate 0.15% ophthalmic solution. Results: Under scotopic conditions (luminance 0.0 candelas [cd]/m²), the pupil diameter decreased by 1.0 mm or more in 100%, 87%, and 60% of eyes at 30 minutes, 4 hours, and 6 hours, respectively (P<.005); under mesopic conditions (luminance 0.2 cd/m²), in 93%, 73%, and 40% of eyes, respectively (P<.005); and under photopic conditions (luminance 150.2 cd/m²), in 73%, 87%, and 67% of eyes, respectively (P<.005). Conclusions: Brimonidine tartrate 0.15% ophthalmic solution produced a significant miotic effect under all 3 luminance conditions. The reproducible miotic effect under scotopic and mesopic conditions may help postoperative refractive patients who report night-vision difficulties related to a large pupil.