Background: Traumatic Brain Injuries (TBIs) are becoming a public health concern due to their rising incidence over the last decade. Diagnosis for TBIs involves clinical evaluation and various tests which can come with their own limitations. Advanced eye-tracking devices can be used to analyze precise eye movements that can expose subtle deficits in visual, motor, and cognitive processes. While ocular motors results in patient with TBI are highly heterogeneous, several studies have revealed a greater number of deficits in non-traditional ocular motor assessments such as anti-saccades, self-paced saccades, memory-guided saccades, auditory reaction time, and visual reaction time tests. When present, however, differences are often subtle and, at times, identified more often by a larger variance in the data rather than a difference in absolute clinical outcomes. We aim to corroborate these findings and further elucidate any salient ocular motor phenotype.
Objective: We compared ocular motor results between TBI patients and healthy controls. Based on previous studies, we predict significant differences in outcomes measures associated with non-traditional ocular motor assessments.
Methods: A total of 32 participants (18 patients with TBI and 14 healthy controls) enrolled for audiovestibular assessment, including ocular motor assessment at the National Institutes of Health Clinical Center between 2018 and 2019. Ocular motor assessment was conducted via a Dx100 three-dimensional liquid crystal display (LCD) head-mounted goggle, formerly known as I-PAS (Neurolign USA, LLC, Pittsburg, PA), with independent biocular 1,920 x 1,080-pixel displays allowing for right and left infrared eye-tracking at a sampling rate of 100 Hz. All eye tracking and motor response rates were captured using Neurolign I-Portal VOG® software (v2019.0.0.12) with real-time data capture and analysis via Neurolign VEST® software (v2019.0.0.14). The participants underwent ocilar motor assessments which were analyzed and presented for this study, anti-saccades, self-paced saccades, horizontal saccades, audio reaction time, visual reaction time, and optokinetic reflex testing.
Results: Statistical differences were identified for anti-saccade error rate (p= 0.05) and 60-degree optokinetic peak eye velocity in both the rightward (p = 0.05) and leftward (p= 0.03) directions between the TBI and control group. All other pairwise and groupwise comparisons including the self-paced saccades, anti-saccades leftward and rightward without error latency mean, auditory and visual reaction time, and the 40-degree and 20-degree optokinetic peak eye velocity were not statistically significant.
Conclusion: Our findings support no overt or ubiquitous ocular motor phenotype in patients with TBI, however we identified significant differences in anti-saccade error rate and optokinetic peak eye velocity using a robust 60-degree per second stimulus. These data support the need for performing non-traditional ocular motor assessments when evaluating patients with TBI, particularly the anti-saccade test. This study supports the growing need for further investigation and usefulness of eye-tracking tests to detect the presence of a TBI.
