The effect of recent concussion history on dynamic visual acuity and balance control in varsity athletes.

Altered visual-cognitive functions and balance control are commonly detected following sport-related concussion (SRC). However, there are no integrated clinical strategies to characterize vision, cognition, and balance beyond the resolution of symptoms for athletes following SRC. To examine how recent SRC history may affect performance for athletes on a dynamic visual acuity (DVA) task while standing. Interuniversity athletes with SRC history who were asymptomatic (SRC = 25; females = 12) were compared to athlete controls (CONTROL = 35; females = 19). A custom DVA program presented a Tumbling "E" moving randomly (RW) or horizontally (H) at 30°/s viewed from 4 m. Athletes identified the target's orientation using a keypad while seated and standing on a force plate (1000 Hz). The lowest target size correctly identified was scored as the log of the minimum angle of resolution (logMAR). Dual-task performance was characterized by, 1) a relative change in DVA logMAR score from seated; 2) response time (RT); and 3) balance control. Balance control was quantified using the root mean square of centre of pressure displacement (dCOP) and standard deviation of high frequency (> 0.4 Hz) component of COP (COP). Athletes with recent SRC exhibited a worse relative change in DVA score from seated to standing for H-motion compared to controls (p < 0.05). However, RT for both motion conditions and balance control were not different between groups. Following SRC, some athletes may have persisting visual-cognitive deficits revealed by a worse change in performance on a horizontal DVA task during increased balance demands while standing.