The use of visual outcome measures may provide benefit as an assessment tool in clinical trials involving neuroimmunological disorders such as neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS), according to a recent review article.
The article, published in Neurology, Neuroimmunology, & Neuroinflammation, highlights the usefulness of different visual outcome measures in the assessment of neurological damage occurring in diseases that can affect the eyes.
“For all paradigms of trials in MS and NMOSD, from standard [disease modifying therapy] trials or those of neuroprotection and remyelination, and even trials of comparative efficacy, applications of visual outcome tools offer cost-effective mechanisms to capture widespread and focal injury across disease subtypes and may lead to more rapid development of new therapeutics for these disabling diseases,” the authors concluded.
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According to the authors, the International MS Visual System Consortium (IMSVISUAL), at least 50% of MS patients experience optic neuritis over the course of the disease and up to 70% will experience efferent dysfunction that may impair eye movements. In NMOSD, nearly half of patients may develop clinical blindness in the first 5 years.
Read more about NMOSD complications.
“Quantification of visual acuity, visual fields, visual quality of life, and electrophysiologic parameters allows assessment of function, whereas optical coherence tomography (OCT) provides reliable measures of the structural integrity of the anterior afferent visual pathway,” the authors suggested.
Visual system assessments can be correlated with other outcome measures, including atrophy, declining cognition, and changes in employment status. Observations of microstructures of the visual system using MRI and optical coherence tomography (OCT) can be more precise than in other parts of the central nervous system, such as corticospinal tracts, and can be more sensitive to changes.
For the measurement of afferent visual function, high- and low-contrast visual acuity can be used to observe clinical changes. Standard static automated perimetry and kinetic perimetry are 2 techniques that can be used to assess changes in visual fields. Different electrophysiological measures including visual evoked potentials and electroretinograms may also be useful tools in the assessment of neurological damage in MS and NMOSD.
The use of eye-tracking devices and software could be beneficial in the measurement of efferent oculomotor dysfunction, as some studies found changes in eye movements before other clinical signs of disability. Eye-tracking has not become widely used yet, possibly due to the variety of device and software options and the lack of a standardized protocol.
Reference
Graves JS, Oertel FC, Van der Walt A, et al. Leveraging visual outcome measures to advance therapy development in neuroimmunologic disorders. Neurol Neuroimmunol Neuroinflamm. 2022;9(2):e1126. doi:10.1212/NXI.0000000000001126
