Changes In Fixational Eye Movements (FEMS) Following Sport-related Concussion

PURPOSE: To evaluate changes in fixational eye movements (FEMs) following sport-related concussion (SRC) and their association to clinical outcomes including recovery time, symptoms, cognitive and vestibular/ocular motor impairment. METHODS: Thirty-three athletes (13-27y; 54.5-F) within 21d of a diagnosed SRC participated in the study. A tracking scanning laser ophthalmoscope (TSLO) evaluated FEMs metrics during fixation on a center and corner target including microsaccades, drift, and bivariate contour ellipse area. Participants completed symptom, cognitive, and vestibular/ocular motor assessments. All measures were administered at initial visit and following medical clearance (clinical recovery). Changes in FEMs were calculated using paired-samples t-tests. Linear regression (LR) models were used to evaluate the association of FEMs with clinical recovery. Pearson product-moment correlations were used to evaluate the associations among FEMs and clinical outcomes. RESULTS: On the center task, changes across time were supported for average microsaccade amplitude (p = .005; Cohen’s d [d] = .53), peak velocity of microsaccades (p = .01; d = .48), peak acceleration of microsaccades (p = .02; d = .48), duration of microsaccade (p < .001; d = .72), and drift vertical (p = .017; d = -.154). The LR model for clinical recovery was significant (R2 = .37; p = .023) and retained average instantaneous drift amplitude (β = .547) and peak acceleration of microsaccade (β = .414). On the corner task, changes across time were supported for drift proportion (p = .03; d = .43). The LR model to predict clinical recovery was significant (R2 = .85; p = .004) and retained average amplitude of microsaccades (β = 2.66), peak velocity of microsaccades (β = -15.11), peak acceleration of microsaccades (β = 12.56), drift horizontal (β = 7.95), drift vertical (β = 1.29), drift amplitude (β = -8.34), drift proportion (β = .584), instantaneous drift direction (β = -.26), and instantaneous drift amplitude (β = .819). FEMs metrics were also associated with nausea and visual memory. CONCLUSIONS: FEMs metrics changed across time following SRC, were useful in predicting clinical recovery, and were correlated with clinical outcomes. FEMs measurements may provide objective data to augment clinical assessments and inform prognosis following SRC.