Eye movement deficits in Multiple Sclerosis: Characterizing executive problems as the disease worsens

Multiple sclerosis (MS) is a progressive inflammatory, demyelinating, immune-mediated disease that causes damage to multiple areas of the central nervous system. This heterogeneity can make its diagnosis challenging and the proper evaluation and early identification of progression difficult. The aim of this study was to investigate whether abnormalities in oculomotor functions evaluated with a novel system using eye-tracking (ET) correlate with physical and cognitive deficits in patients with MS.

This cross-sectional evaluation was performed at the Ramos Mejía Hospital, Buenos Aires, Argentina. Analysis of eye movements of 71 MS patients at different stages of MS were recorded and analyzed during a Go/No-Go visual task with the ViewMind® system, a software as a medical device (SaMD) using a Head Mounted Display (HMD) with ET capability. The percentage of single fixations (SF), re-fixations (RF), trial duration, and total number of fixations were analyzed and compared to traditional assessments of clinical cognitive and motor performance (the Expanded Disability Status Scale (EDSS), Symbol Digit Modalities Test (SDMT), Paced Auditory Serial Addition Test (PASAT), California Verbal Learning Test (CVLT) and the Brief Visuospatial Memory Test-revised (BVMT)).

A significant correlation was found between all measured eye movements and the scores of the traditional cognitive and motor performance tests. The percentage of SF decreased whereas the number of fixations, percentage of RF and trial duration increased along with the worsening of motor and cognitive disabilities.

The strong correlation between oculomotor parameters during a Go/No-Go visual task and traditional clinical test scores suggests that eye movement evaluation may provide a reliable, fast, and objective tool for assessing cognitive and motor impairments in people with MS. Further research, including longitudinal studies, is necessary to determine its utility in monitoring disease progression.