Effect of Pupil Size and Binocular Viewing on Accommodative Gain in Emmetropia and Myopia.

To evaluate the differences in accommodative gain in response to different accommodative stimuli and determine the effects of pupil size, binocular viewing, and inherent eye refraction on accommodative gain. This study enrolled 47 healthy young adults (emmetropia: 21 eyes, myopia: 26 eyes). Refractive value and pupil size during accommodative stimulus were measured using an open-viewing type auto-refractor (Grand Seiko WAM-5500). The subject was continuously presented with six stimuli (0D, 1D, 2D, 3D, 4D, and 5D) in front of the eye. Measurements were performed under three conditions. Condition 1: Monocular status with complete occlusion of the non-viewing eye; Condition 2: Monocular status with occlusion of the non-viewing eye by translucent occluder; Condition 3: Binocular status. In the emmetropia group, there was no significant difference in accommodative gain between conditions 1 and 2 ( The effects of pupil size and binocular viewing on accommodative gain differed between emmetropia and myopia.