J Mult Scler Res. 2024; 4(3): 59-66 | DOI: 10.4274/jmsr.galenos.2024.2024-12-1

The Relationship Between Retinal Layer Thickness and Cognition in People with Multiple Sclerosis

Sinem Ozcelik¹, Ergi Kaya², Denizcan Ozizmirliler³, Furkan Guney⁴, Ozge Sagici⁵, Aylin Yaman⁶, Cavid Baba^7
1Tufts Medical Center, Department of Neurology, Boston, Massachusetts, USA
²Dokuz Eylul University Faculty of Medicine, Department of Neurology, Izmir, Turkey
³Nevruz Erez State Hospital, Clinic of Ophthalmology, Igdir, Turkey
⁴Dunyagoz Hospital, Clinic of Ophthalmology, Istanbul, Turkey
⁵Dokuz Eylul University Graduate School of Health Sciences, Izmir, Turkey
⁶Dokuz Eylul University Faculty of Medicine, Department of Ophthalmology, Izmir, Turkey
⁷Urla State Hospital, Clinic of Neurology, Izmir, Turkey

INTRODUCTION: Optical coherence tomography (OCT) and OCT-angiography (OCT-A) are non-invasive techniques for investigating retinal layers and blood flow. Axonal loss in neurodegenerative disorders like multiple sclerosis (MS) can be evaluated with OCT. The retinal nerve fiber layer (RNFL) and ganglion cell inner plexiform layer (GCIPL) are mainly affected layers by MS-related axonal loss. As a result, these layers can be a biomarker of disability, cortical volume and cognition in people with MS (pwMS). This study investigates the relationship between cognition and retinal nerve layers’ thickness and retinal vessel density in pwMS.
METHODS: The participants’ OCT and OCT-A examinations were evaluated retrospectively. The participants with a history of bilateral optic neuritis and less than 12 years of education were excluded from the study. The participants were divided into the following two groups: pwMS with optic neuritis (ON+) and pwMS without optic neuritis (ON-). The unaffected eyes were evaluated in the ON+, and the mean values of eyes were evaluated in the ON- group. Demographic variables, Expanded Disability Status Scale (EDSS) and Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS), which include: Symbol Digit Modalities Test (SDMT), Brief Visuospatial Memory Test-Revised (BVMT-R), California Verbal Learning Test-II (CVLT-II) were examined.
RESULTS: Twenty-eight participants were in the ON+ group, and 56 pwMS were in the ON- group. The thickness of GCIPL inferior and temporal quadrants exhibited a weak negative correlation with BVMT-R in the ON-group. The vessel density of optic disc inferior quadrant results showed a weak positive correlation with SDMT in the ON-group (ρ=0.329, p=0.02). The superonasal quadrant of RNFL had a moderate negative correlation with the results of CVLT-II in the ON+ group (ρ=-0.458, p=0.016). On the other hand, GCIPL, in all quadrants except the centrum, positively correlated with SDMT in the ON+ group. Similar correlation results were detected between the inferotemporal/global thickness of RNLF and SDMT in the ON+ group.
DISCUSSION AND CONCLUSION: The thicknesses of specific quadrants of RNFL and GCIPL might have a weak to moderate correlation with information processing speed, particularly in ON+ pwMS. Only inferior quadrant optic disc vessel density showed a weak correlation with information processing speed in ON- group.

Keywords: Optical coherence tomography, optical coherence tomography-angiography, cognition, multiple sclerosis

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