Oculomotor markers of functional impairment in traumatic brain injury using simple and predictive visual tracking

Oculomotor function is a sensitive marker of neurological impairment, and smooth pursuit deficits have been reported across multiple neurological disorders. However, the oculomotor deficits following traumatic brain injury (TBI) remain incompletely characterized, particularly in relation to current functional status during rehabilitation.

In this study, we employed a bedside, head-free eye-tracking paradigm based on short, repeated linear tracking segments, to assess oculomotor dysfunction in 30 TBI patients undergoing inpatient rehabilitation and 30 age-matched controls. This design enabled the extraction of multiple complementary oculomotor indices, including saccadic pursuit (catch-up saccade contribution), tracking deviation under occlusion, initial tracking speed, initial catch-up saccade latency, pupil response, and vergence instability.

TBI patients exhibited widespread deficits across these indices compared with controls (AUC = 0.71-0.84). These measures also correlated significantly with functional status as indexed by the Functional Independence Measure (R = 0.39-0.77, p < 0.001) but, importantly, showed no association with initial injury severity as indexed by the Glasgow Coma Scale.

These findings indicate that TBI disrupts multiple components of the oculomotor system, extending beyond basic pursuit gain to predictive tracking, pupil-linked arousal, and binocular coordination. The dissociation between functional status and initial acute injury severity highlights the sensitivity of oculomotor measures to current brain function during rehabilitation. Together, these results support the use of brief, clinic-friendly eye-tracking assessments as a quantitative approach for evaluating current functional status in TBI, with potential future applications for longitudinal monitoring pending further validation.