ASB clinical biomechanics award winner 2016: Assessment of gaze stability within 24–48 hours post-concussion

The Measurement of Eye Movements in Mild Traumatic Brain Injury: A Structured Review of an Emerging Area

“…Eye movements in the reviewed articles were measured using a variety of eye-tracking instruments, which largely depended on the desired eye-movement outcome or task being evaluated. For example, stationary eye-trackers were used for activities where restricted head movement was required, whereas mobile eye-trackers tended to be used for tasks that allowed head movement (i.e., walking or playing a computer game while standing balance was also examined; Murray et al, 2014 , 2017 ; Stuart et al, 2019b ). The 22 articles described an array of instrumentation including desk or computer-mounted infrared eye-trackers, rotary chairs within enclosed rooms, tethered head-mounted eye-trackers and fully mobile eye-trackers ( Table 2 ).…”

“…Yet, the influence of mTBI on specific outcomes was inconsistent. For example, several studies found deficits in saccades in people with mTBI during anti-saccadic tests (Johnson et al, 2015a , b ; Balaban et al, 2016 ; DiCesare et al, 2017 ; Hoffer et al, 2017 ; Murray et al, 2017 ; Webb et al, 2018 ), whereas others found no differences (Wetzel et al, 2018 ; Cochrane et al, 2019 ; Kelly et al, 2019 ). Studies that did not find differences, however, may have been impacted by methodological issues, such as grouping all stages of mTBI together (acute/sub-acute and chronic) to make a larger cohort (Wetzel et al, 2018 ; Kelly et al, 2019 ), which limits comparison and understanding of potential deficits at different stages.…”

“…None of the reviewed articles controlled for the impact of cognition or basic visual function (visual acuity or contrast sensitivity) on eye movements, and only one study (Stuart et al, 2019b ) reported basic visual function scores. Many of the studies did not assess cognition and similarly many only reported that they excluded subjects based on visual function (i.e., eye chart screening or self-reported questionnaires) but provided no scores or results to verify this (Suh et al, 2006 ; DiCesare et al, 2017 ; Murray et al, 2017 ; Howell et al, 2018 ; Webb et al, 2018 ; Wetzel et al, 2018 ; Cochrane et al, 2019 ; Kelly et al, 2019 ). None of the studies provided any information on the use of corrective eye wear by the participants during the eye-tracking assessments, with several articles reporting that subjects had “normal or corrected to normal vision,” but it was unclear if individuals with vision correction were included in reported results.…”

“…Despite the huge number of outcome measures reported, many of the outcomes were reported in a task-dependent manner. For example, static seated eye-movement assessments tended to comprehensively report many outcomes from long testing protocols, whereas dynamic standing or walking tasks tended to report a small number of largely saccadic outcomes (e.g., saccade number, velocity, amplitude; Murray et al, 2014Murray et al, , 2017Stuart et al, 2019b). This task-dependent reporting of eye-movement outcomes likely stems from the complexity of data processing and analysis with increasingly dynamic tasks (Zhu and Ji, 2005;Stuart et al, 2014bStuart et al, , 2019a.…”

“…Comparison of several studies that reported saccade velocity indicated that there may be task-dependent mTBI impairments. For example, seated studies reported reduced saccadic velocity in mTBI compared to controls (Cifu et al, 2015 ; Cochrane et al, 2019 ; Kelly et al, 2019 ), whereas dynamic studies reported the opposite (i.e., greater saccadic velocity in mTBI; Murray et al, 2017 ). However, due to the limited number of studies available for review and methodological variations, definitive conclusions cannot currently be drawn.…”