Visuo-oculomotor Function and Reaction Times in Athletes with and without Concussion

Abstract

Significance: Oculomotor tests in concussion commonly show impairment in smooth pursuit and saccadic function. Honing in on the systems likely to be affected by concussion will streamline use of oculomotor function as a supplemental diagnostic and prognostic tool, as well as improve our understanding of the pathophysiology of concussion.

Purpose: This study investigates oculomotor function between concussed and healthy collegiate athletes and determines measurement test-retest reliability of those tools.

Methods: Eighty-seven healthy athletes were recruited from a U.S. Division 1 sports university and completed a 30-minute vestibular ocular testing battery in an enclosed rotary chair system equipped with 100-Hz eye-tracking goggles. Forty-three individuals completed the battery twice. Twenty-eight individuals with a current diagnosis of concussion also completed the battery. All participants were aged 18 to 24 years. Bivariate statistical tests examined differences in scores across groups, and intraclass coefficients were computed to test reliability.

Results: Concussed individuals had significantly longer saccadic, visual, and dual-task reaction times and reduced saccadic accuracy. There was no difference in optokinetic reflex gain, but few concussed individuals tolerated the task. Reaction time latencies and optokinetic gain show moderate test-retest reliability. Smooth pursuit tasks and saccadic accuracies showed poor test-retest reliability.

Conclusions: Saccadic latency was the most sensitive oculomotor function to change after concussion and was reliable over time. Saccadic accuracy was significantly lower in the concussed group but had poor retest reliability. Optokinetic gain may warrant more investigation because of its high test-retest reliability and symptom provocation in concussion, despite not showing a significant difference between groups.

Figure 1.

Correlation between Position Gain on first and second administration of 0.1Hz Horizontal Smooth Pursuit task in 40 healthy individuals. Intraclass Correlation Coefficient (ICC) = 0.09 (range=0.00-0.78), Smallest real difference = 19.0%. Note the very tight spread of data (with 3 outliers) vs Figure 2.

Figure 2.

Correlation between Position Gain on first and second administration of 1.0Hz Horizontal Smooth Pursuit task in 40 healthy individuals. Intraclass Correlation Coefficient (ICC) = 0.71 (range=0.53-0.84), Smallest real difference = 19.3%. Note the wide spread of data vs Figure 1 which results in a much stronger ICC but essentially identical smallest real differences between tasks.