Abnormal eye movements increase as motor disabilities and cognitive impairments become more evident in Multiple Sclerosis: A novel eye-tracking study

Background Eye movements can reflect brain alterations and inform on the presence of motor disabilities and cognitive impairments in people with multiple sclerosis (pwMS). Objective The aim of the study was to determine the correlation between motor and cognitive measurements and eye movement parameters when performing the n-back task (NBKT). Methods This was a cross-sectional study carried out at Ramos Mejía Hospital, a center specialized in demyelinating diseases in Buenos Aires, Argentina. The study population consisted of 66 patients with relapsing-remitting multiple sclerosis (RRMS) and 5 patients with secondary progressive multiple sclerosis (SPMS). pwMS performed the n-back test while using a device head mounted display (HMD) with eyetracking capabilities in order to capture eye movement. Clinical motor and cognitive measures were assessed with Expanded Disability Status Scale (EDSS), Nine Hole Peg Test (NHPT), Timed 25-Foot Walk (T25FW), and Symbol Digit Modalities Test (SDMT). Results pwMS showed strong and statistically significant correlations between gaze duration; number of fixations, saccade amplitude and motor disabilities and cognitive impairments as measured by EDSS, NHPT, T25FW, and SDMT. Conclusion This study found significant correlations between eye movement behavior and motor and cognitive disability in pwMS. These findings suggest that eye movements have the potential to be used as a surrogate biomarker in MS progression.