Purpose: Visual impairments affect up to 90% of patients post-concussion and may include deficits in fixation accuracy, smooth pursuit, saccadic latencies, vergence, accommodation, or vestibule-ocular reflexes. Quantitative assessment of oculomotor function may provide a sensitive measure of concussion recovery since coordinated eye movements require the use of diverse and widely dispersed areas of the brain. This study quantified oculomotor function over time in adolescents following concussion, hypothesizing that initial deficits would resolve by the time of RTP and remain stable after RTP.
Methods: 13 adolescent athletes with mild to moderate concussion (7 male; mean age 15.1, SD 2.1, range 10-17 years) were prospectively evaluated at their initial visit (mean 18, range 4-43 days post-concussion), at the time of RTP clearance (mean 46, range 12-173 days post-concussion), and one month later (mean 26, range 20-41 days after RTP). 11 controls without past concussion or injury (3 male; mean age 12.3, SD 3.1, range 8-17 years) were tested at similar timepoints. Eye tracking was recorded as subjects followed a target moving on a screen in predefined patterns related to sinusoid and trapezoid smooth pursuit, vergence, saccade, and anti-saccade. Metrics characterizing the speed, accuracy, and variability of tracking were compared between groups and visits using t-tests and linear mixed-effects regression.
Results: At baseline, patients tended to have greater overshoot and greater variability in tracking compared with controls, though the differences were not statistically significant. Overshoot (coef -1.97, SE 0.98, p=0.045), variability of tracking (-1.04, SE 0.53, p=0.048), and variability of overshoot (-2.59, SE 1.04, p=0.013) decreased from baseline to RTP. Undershoot during sinusoid smooth pursuit tended to decrease from RTP to 1-month follow-up (-0.16, SE 0.09, P=0.080). The rate of convergence in the distance vergence task increased (0.27, SE 0.10, p=0.005) while the rate of divergence decreased (-0.32, SE 0.17, p=0.068) between these time points.
Conclusion: Possible deficits in eye tracking resolved by the time of RTP and generally remained stable or continued improving after RTP, suggesting that oculomotor function recovers sufficiently under current conservative treatment protocols.