Effects of a Single Dose of Topical Brimonidine 0.15% on Anterior Segment Morphology, Pupil Characteristics, and Choroidal Thickness in Healthy Subjects

Purpose: To investigate the effects of a single dose of brimonidine 0.15% on anterior segment morphology, pupil characteristics, and choroidal blood flow in treated and untreated eyes of healthy subjects and to compare the results obtained with those in another healthy volunteer group. Methods: Participants were classified as study and control groups. The eyes in the study group were randomized. Only one eye received one drop of brimonidine (treated eyes), and the contralateral eye received single dose of sodium hyaluronate (untreated eyes). In addition, only right eyes of control subjects, who had single dose of sodium hyaluronate to both eyes, were analyzed (control eyes). Anterior segment parameters including central corneal thickness (CCT), aqueous depth, anterior chamber volume, iridocorneal angle (ICA), horizontal anterior chamber diameter, and pupil measurements including scotopic, mesopic, photopic, and dynamic pupil diameters (PDs) were performed with Sirius Scheimpflug camera. Choroidal thickness (CT) measurements were taken with optical coherence tomography. These measurements were taken at baseline and repeated 1 hour after the dosing. Results: Only the treated eyes had significantly thicker CCT and wider ICA values after instillation of brimonidine. Static and dynamic PD values of treated eyes and even untreated eyes significantly decreased after brimonidine. However, brimonidine has no significant effect on CT measurements. Conclusion: A single dose of brimonidine causes thickening in CCT and widening in ICA values in treated eyes. In addition, it has significant effect to decrease the scotopic, mesopic, photopic, and dynamic PD values in treated and even contralateral eyes while has no effect on choroidal blood flow.