Interocular Timing Differences in Horizontal Saccades of Ball Game Players.

In ball game sports, binocular visual function is important for accurately perceiving the distance of various objects in visual space. However, the temporal coordination of binocular eye movements during saccades has not been investigated extensively in athletes. The purpose of the present study was to compare the characteristics found in the interocular timing differences in horizontal saccades between ball game players. The participants included 32 university baseball players and 54 university soccer players. They were asked to shift their gaze to the onset of the light-emitting diodes located at 10 deg of visual field eccentricity to the left and right and alternated every 2 s. Horizontal movements of the left and right eyes were recorded separately with the electro-oculogram. Temporal variables for each eye were calculated with digital differentiation, and timing differences between the left and right eyes were compared between participant groups. The overall results showed significant interocular differences between left and right eye movements for the temporal variables of binocular saccades. The comparison between the participant groups revealed that baseball players had smaller interocular timing differences between the left and right eyes than soccer players in the onset time, time to peak velocity, duration, and peak velocity. These results suggest that baseball players have a higher degree of temporal coordination in binocular eye movements, particularly during the initial phase of horizontal saccades, compared to soccer players. This enhanced coordination might be attributable to the sport-specific visual demands of baseball, where players require precise stereoscopic vision to track a small high-speed ball within their visual space.