Eye scans link retinal thinning to slower cognitive processing in MS
Study highlights tests as possible tool for monitoring neurodegeneration
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Thinning of a layer of nerve cells in the eye's retina was associated with slower information processing in people with multiple sclerosis, independent of physical disability, a study found.
- Thinning of the retinal nerve fiber in multiple sclerosis is linked to slower cognitive processing speeds.
- This retinal neurodegeneration occurs independently of physical disability, a study reports.
- These findings highlight eye scans as a potential noninvasive monitoring tool for cognitive decline.
Thinning of a layer of nerve cells in the retina, the light-sensitive tissue at the back of the eye, was associated with slower information processing in people with multiple sclerosis (MS), independent of physical disability, a study found.
Researchers concluded that the findings support retinal imaging as a potential tool for monitoring neurodegeneration in MS.
The study, “Retinal nerve fiber layer and ganglion cell layer thinning as biomarkers of cognitive decline in multiple sclerosis: an 18-month prospective cohort study,” was published in the journal Multiple Sclerosis and Related Disorders.
Cognitive problems affect an estimated 40% to 60% of MS patients
MS is an inflammatory disease marked by the progressive loss of nerve fibers in the central nervous system (CNS), which comprises the brain and spinal cord.
Cognitive problems affect an estimated 40% to 60% of people living with MS and can interfere with memory, attention, information-processing, employment, and daily life. Yet, cognitive decline may go undetected, and readily accessible biomarkers to identify it early are lacking.
The retina is considered an extension of the CNS. Optical coherence tomography (OCT) is a noninvasive imaging test that can measure the thickness of retinal layers, including the retinal nerve fiber layer (RNFL), which contains nerve cell fibers, and the ganglion cell layer (GCL), which contains the bodies of retinal cells. Thinning of these layers has previously been associated with neurodegeneration and brain tissue loss in MS.
In this study, researchers in Argentina sought to determine whether RNFL and GCL thickness are associated with cognitive performance in people with MS who had never experienced optic neuritis, or inflammation of the optic nerve.
Patients with normal RNFL thickness performed better on dexterity test
The study enrolled 70 adults with MS between 2022 and 2024 at a center in Buenos Aires. Sixty-one (mean age 41.2, 72.1% women) completed the 18-month follow-up. Most patients (93.4%) had relapsing-remitting MS, with a mean disease duration of 5.9 years. At the study’s start (baseline), 37 patients (60.7%) met criteria for cognitive impairment.
Participants underwent OCT eye scans and a series of cognitive tests at the start of the study and again 18 months later.
At baseline, 27 patients (44.3%) had abnormally thin RNFL measurements, while 26 (42.6%) had abnormal GCL thickness. Over the 18 months, the researchers detected modest a thinner RNFL in the left eye, but no significant overall changes in GCL thickness.
Having a thicker GCL was associated with better performance on the PASAT-3, a test that assesses information-processing speed and working memory. After correcting for multiple statistical comparisons, this was the only retinal-cognitive association that remained statistically significant.
[Further prospective studies with] longer follow-up, and larger samples are required to validate predictive cutoffs for clinically meaningful retinal and cognitive decline.
The relationship also remained significant after the researchers accounted for age, education, and scores on the Expanded Disability Status Scale (EDSS), a commonly used measure of MS-related disability.
This suggests that retinal nerve-cell loss may capture aspects of nervous system damage that are not fully reflected by physical disability measures, according to the researchers.
Participants with normal RNFL thickness also performed better at baseline on the PASAT-3 and the Nine-Hole Peg Test, which measures hand and finger dexterity, than those with abnormal RNFL thickness.
Over 18 months, phonemic verbal fluency — the ability to rapidly generate words from memory beginning with a particular letter — improved by four points among participants with normal RNFL thickness, while remaining essentially unchanged in those with abnormal RNFL. However, this represents a trend rather than a statistically significant difference, the scientists noted.
Overall, these findings represent preliminary evidence supporting the incorporation of OCT into “monitoring strategies for disease progression in MS,” the researchers wrote.
However, further prospective studies with “longer follow-up, and larger samples are required to validate predictive cutoffs for clinically meaningful retinal and cognitive decline,” they concluded.
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