## 2 Materials and Methods
_The Patient Reported Outcomes Measurement Information System_ (_PROMIS_) [45] was used to measure the current psychological functions (i.e., depression, anxiety, and sleep disturbances in past 7 days). The PROMIS is a highly reliable, precise measure of patient-reported health status for physical, mental, and social well-being. Three domain measures from PROMIS--depression, anxiety, and sleep disturbances--were used. Each domain measure has undergone rigorous qualitative and psychometric evaluation and refinement through numerous clinical studies, providing efficient, precise, valid, and responsive indicators of a person's health status. As a standing balance measure, a _force platform_ (FP4060-05-PT) was used to acquire characteristics of bipedal standing balance test. Following the customized method and procedure described in [PERSON] et al. (2017) and [PERSON] et al. (2017) [46; 47], we asked the subject to stand still on the force plate with barefoot for 120 s with crossing their upper limbs against their chest and focusing theirvision on a static point at eye level. The task was performed while the subject stood vertically on the top of a force platform while the coordinates of the body's center of pressure (CoP) were recorded. The force plate provided data of horizontal and vertical components of the ground reaction force (Fx, Fy, Fz) and the moments of force around the frontal, sagittal and vertical axes (Mx, My, Mz). These data were used to compute postural sway based on instantaneous CoP location during the standing task in both anterior-posterior and medio-lateral directions (CoP\({}_{\text{AP}}\) and CoP\({}_{\text{ML}}\), respectively). Adapting [PERSON] et al. (2017) and [PERSON] et al. (2017)[46; 47], the following variables of interest were extracted from CoP coordinates and used in analysis: the area of CoP path (_Area_), the peak-to-peak amplitude of the CoP displacement in each direction (_Amplitude_AP and _Amplitude_ML), the mean velocity of the CoP displacement in each direction (_MVAP_ and _MVML_), the frequency at which 80% of the CoP spectral power for each direction (_F80\({}_{\text{AP}}\)_ and _F80\({}_{\text{ML}}\)_), the sample entropy estimates of the CoP displacement in each direction (_SEnt\({}_{\text{AP}}\)_ and _SEnt\({}_{\text{ML}}\)_), and the cross-sample entropy (CrossSEnt) representing the degree of asynchrony or dissimilarity between CoP\({}_{\text{AP}}\) and CoP\({}_{\text{ML}}\) signals in time. For examining visual function, a trained optometric assistant screened each subject's visual function using the two following approaches:  
1. _King-Devick Oculomotor Test_--Testing the eye's ability to 'track' or move accurately and efficiently from one point to the next [48]. The test has three sections, which include numbers with guides, numbers without guides, and numbers without guides and with irregular spacing. The subject was timed while reading the numbers left to right, and errors were monitored until the subject completed reading aloud each slide. Initially derived by an optometrist, the test is becoming an increasingly popular interdisciplinary test among professionals working with individuals with mTBI or concussion [48; 49]. 2. _Binocular Accommodative Facility with +2.00/-2.00 Flipper Lens_--Testing the ability of the eye's ability to accommodate (or, 'focus' and'make clear') when simulating near and far distances using a special set of lenses. The visual system's ability to dynamically focus at different distances (i.e., with close proximity while reading or at the distance when looking toward a street sign) is a visual skill, which may be impacted in mTBI. Inefficiencies may be demonstrated by perceiving double vision upon adjusting focus through the lens, inability to clear a lens (either minus which simulates near focus, or the plus lens which simulates distance focus), or an increased length of time to clear either or both sides.