Abstract
Purpose :
Eye movements may offer a sensitive method to detect abnormalities and measure response to intervention in mild traumatic brain injury (mTBI).
Methods :
The Brain Injury and Mechanisms of Action of Hyperbaric Oxygen for Persistent Post-Concussive Symptoms after Mild Traumatic Brain Injury Study (BIMA) randomized 71 participants to 40 daily sessions of hyperbaric oxygen or sham. A companion normative population study enrolled 75 participants. An eye tracking system (EyeLink II, SR Research, Ottawa, Canada) was used to measure eye movements at baseline, 13 weeks and 6 months. Left and right eye movements were recorded for up to 34 parameters for 11 tracking tasks including both saccadic and smooth pursuit. Results were considered significant if t-tests for at least one eye was significant at p<0.001 and the contralateral eye at p<0.02 as confirmatory evidence to informally adjust for multiple testing.
Results :
All but 5 of the 34 circular test parameters, 4 of the horizontal ramp, 6 of the vertical ramp, and 13 of the reading task had significantly worse performance in the BIMA population compared to the normal population. On average BIMA participants read fewer lines than normative participants (OD: 44.3 versus 47.8 lines, p=0.04), averaged more fixations (OD: 6.9 versus 6.1, p=0.005) and more regressions per line (OD: 3.8 versus 3.1, p=0.0003). At 13 weeks and 6 months, BIMA participants, regardless of intervention, shifted towards the normal population distribution for the circular, and the horizontal and vertical ramp tasks. The reading task continued to suggest abnormalities. There were no differences between the hyperbaric and sham arms in performance at any time point.
Conclusions :
Circular, horizontal and vertical ramp, and reading tasks were the most sensitive in differentiating between the normative and BIMA participants, suggesting potentially greater vulnerability of the smooth pursuit system to mTBI compared to the saccadic system. Following intervention, BIMA participants on both intervention arms experienced improved performance on the circular, horizontal and vertical ramp tasks such that differences from the normal participants were no longer evident. The improvement did not differ significantly between the two interventions at any post intervention timepoint.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.