Comparing fixational stability of D1 baseball players as measured by Tracking Scanning Laser Ophthalmoscopy to healthy controls

Abstract

Purpose : To compare Tracking Scanning Laser Ophthalmoscopy (TSLO) measurements of eye fixation in elite D1 baseball players against a control group of healthy, non-baseball players as a preliminary investigation into the mechanism of Quiet Eye.

Methods : Thirty-four young, healthy control subjects (CS) (19F, 15M) aged 13-27 and 26 male D1 baseball players (BP) aged 18-22 participated in the study. For the CS analysis, two 30-second videos were split into three, separate 10-second recordings. Subjects were instructed to fixate on the upper right corner of a 5°x 5° 840nm imaging raster. For the BP, at least three 10-second videos were recorded per eye utilizing the same fixation stimuli and instructions as the CS. Offline, custom MATLAB software was used to stabilize the videos, extract eye motion at 480Hz, and compute microsaccade amplitude, peak velocity, peak acceleration, drift proportion, and drift amplitude. The bivariate contour ellipse area (BCEA) was calculated for each participant.

Results : A mixed effects model was conducted for each fixation measure to see if there was a difference in means (SD) between BP versus CS. Microsaccade mean amplitude was 0.30° (0.15) vs 0.46° (0.21) for BP vs CS (p<0.005). Microsaccade mean peak velocity was 38.99°/sec (24.85) vs 79.68°/sec (49.13) for BP and CS (p<0.0005). Microsaccade peak acceleration was 10510.05°/sec² (9742.58) vs 30997.33°/sec² (22431.55) for BP vs CS (p<0.0001). Drift proportion was 0.88 (0.09) vs 0.84 (0.08) for BP vs CS (p<0.05). BCEA of the drift was 0.10°² (0.13) vs 0.22°² (0.21) for BP vs CS (p<0.005). There was no statistically significant difference in drift amplitude between BP and CS.

Conclusions : D1 baseball players exhibited more stable fixations in performing the given fixation task on TSLO as demonstrated by smaller mean microsaccade amplitudes, velocity, acceleration, and greater drift proportion. Whether this increased fixational stability is the result of an innate ability or is the result of the visual training required to play the visually demanding sport of baseball is still undetermined and warrants further investigation. Additional evaluation of eye motion with TSLO may provide promising insight into the mechanisms of Quiet Eye and on-field performance for baseball players in sports vision.

This is a 2021 ARVO Annual Meeting abstract.