J Neurotrauma. 2023 Aug 11. doi: 10.1089/neu.2023.0080. Online ahead of print.
Concussions often involve ocular impairment and symptoms such as convergence insufficiency, accommodative insufficiency, blurred vision, diplopia, eye strain and pain.- Current clinical assessments of ocular function and symptoms rely on subjective symptom reporting and/or involve lengthy administration time. More objective, brief assessments of ocular function following concussion are warranted. The purpose of this study was to evaluate changes in fixational eye movements (FEMs) and their association to clinical outcomes including recovery time, symptoms, cognitive and vestibular/ocular motor impairment. Thirty-three athletes (13-27y; 54.5-F) within 21d of a diagnosed concussion 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 (Post-Concussion Symptom Scale [PCSS]), cognitive (Immediate Post-concussion Assessment and Cognitive Testing [ImPACT], and Vestibular/Ocular Motor Screening (VOMS). All measures were administered at the 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. 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. The FEMs metric were also associated with PCSS, ImPACT, and VOMS clinical concussion outcomes with the highest magnitude correlations between average saccade amplitude and VOMS symptoms of nausea and average instantaneous drift speed and ImPACT visual memory respectively. FEMs metrics changed across time following concussion, 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 this injury.