Abstract
Concussions are a common injury amongst athletes, causing impairments of motor and cognitive functions. Current methods of diagnosing and tracking recovery of concussion are mainly based on cognitive tests that show important learning effects. Since frontal and occipital lobes are likely affected by a concussion, and given that those regions are involved in eye movements, we hypothesize that eye movements are disrupted by a concussion. We assessed different aspects of eye movements (single saccade-fixation, pursuit, and microsaccades induced by the Troxler effect) in athletes with a recent concussion ([[lt]]2 weeks), athletes with history of older concussions (1–5 years), and individuals without a history of concussion. Our findings indicate no difference amongst the three groups on the single saccade-fixation task. In contrast, whilst horizontal tracking of a slow or fast moving target is normal, the oculomotor pursuit of a single target moving either vertically or in a circular manner is abnormal in concussed athletes, with the greatest deficits in the recently concussed athletes. Athletes with a concussion make fewer saccades and fixations, have longer fixation durations, and greater saccade amplitudes. For the Troxler effect, in comparison to the control group, concussed athletes experience a more rapid onset, and the effect lasts longer. Finally, concussed athletes show suppression in the number and amplitude of microsaccades. Therefore, although concussions are often considered as transient and without long-term consequence, our results indicate persistent dysfunction in the brain regions involved in certain aspects of eye movements.