Effect of pupil size on visual function under monocular and binocular conditions in LASIK and non-LASIK patients

Abstract

Purpose To compare binocular and monocular vision in patients treated with laser in situ keratomileusis (LASIK) and in non-LASIK patients. Setting Jules Stein Eye Institute, Los Angeles, California, USA. Methods This comparative cross-sectional study comprised 20 postoperative LASIK patients and 20 non-LASIK ametropic patients. LogMAR visual acuity, contrast sensitivity, and infrared pupillometry were tested. Outcome measures were better-eye monocular acuity, binocular acuity, better-eye contrast sensitivity, binocular contrast sensitivity, and pupil diameter under monocular and binocular conditions. Results Binocular visual acuity and contrast sensitivity were statistically significantly better than the visual acuity in the better eye ( P = .0047 to <.0001) in both patient groups. Pupil diameter was statistically significantly smaller under the binocular condition than the monocular condition ( P <.0001) in both groups. Conclusions Monocular testing induced larger pupil diameters, which was associated with reduced vision compared to binocular measurements in LASIK and non-LASIK patients.