Pupil size effect on binocular summation for visual acuity and light disturbance.

Purpose: Smaller pupil size under binocular conditions could justify partially the improvement of visual performance when compared to monocular conditions. The purpose of this study was to assess the binocular summation for increasing levels of spherical and cylindrical defocus when the pupil size factor is ruled out as a confounding factor.

Methods: Fifteen young subjects were recruited in this crossover study.