Association of retinal vessel pathology and brain atrophy in relapsing-remitting multiple sclerosis

MOG35 - 55-induced EAE model of optic nerve inflammation compared to MS, MOGAD and NMOSD related subtypes of human optic neuritis

Optic neuritis (ON), or inflammation of the optic nerve, is a common presenting symptom of demyelinating neuroinflammatory conditions that result in significant, subacute vision loss. Given its association with visual impairment and varying extent of visual recovery, ON has been recognized as a significant health burden with a need for new therapeutic strategies to improve long-term visual outcomes. Among the resources utilized to study ON, animal models have emerged as powerful tools to examine the underlying pathophysiology and the effectiveness of proposed therapies. In the current review, we discuss the functional and structural phenotypes related to ON in currently used mouse models, and summarize how the pathophysiology and visual phenotype of the myelin oligodendrocyte glycoprotein 35-55 (MOG35 - 55) experimental autoimmune encephalomyelitis (EAE) mouse model recapitulates clinical features of multiple sclerosis (MS), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and neuromyelitis optica spectrum disorder (NMOSD). The location of ON and the amount of visual recovery in the EAE model most closely resembles MS and NMOSD. However, we propose that the MOG35 - 55-induced EAE model of ON is primarily a MOGAD model given its similarity in pathophysiology, spinal cord demyelination pattern, and the degree of vision loss, retinal nerve fiber layer (RNFL) swelling, and disc edema. Overall, the MOG35 - 55-induced EAE animal model demonstrates overlapping features of autoimmune demyelinating conditions and serves as a comprehensive tool to further our understanding of visual impairment in all three conditions.

The relationship between optical coherence tomography and magnetic resonance imaging measurements in people with multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Several studies show that optical coherence tomography (OCT) metrics e with cognition, disability, and brain structure in people with multiple sclerosis (PwMS). This review the correlation between OCT parameters and magnetic resonance imaging (MRI) measurements in PwMS.

METHODS

A comprehensive search of PubMed/MEDLINE, Embase, Scopus, and Web of Science was performed, including studies published in English up to November 29, 2024 to identify studies reporting quantitative data on the correlation between baseline OCT parameters and MRI measurements in PwMS. The meta-analysis was performed using R software version 4.4.0.

RESULTS

From 4931 studies, 68 studies on 6168 PwMS (67.4 % female) were included. The most significant correlations were found between peripapillary retinal nerve fiber layer (pRNFL) thickness and lower T1 lesion volume r = -0.42 (95 % CI: -0.52 to -0.31, p-value <0.001, I2 = 24 %), greater thalamic volume r = 0.39 (95 % CI: 0.17 to 0.61, p-value <0.001, I2 = 81 %), and lower T2 lesion volume r = -0.37 (95 % CI: -0.54 to -0.21, p-value <0.001, I2 = 85 %), respectively. Additionally, lower macular ganglion cell-inner plexiform layer (mGCIPL) thickness showed the most significant correlations with positive and lower thalamic volume r = 0.37 (95 % CI: 0.1 to 0.64, p-value = 0.008, I2 = 88 %), and positive and lower grey matter volume (GMV) 0.33 (95 % CI: 0.15 to 0.52, p-value <0.001, I2 = 81 %), respectively.

CONCLUSION

pRNFL and mGCIPL thickness are correlated with MRI measurements, suggesting that OCT can serve as a non-invasive, cost-effective, and complementary tool to MRI for enhancing the exploring of brain structural changes in PwMS.

Longitudinal analysis of retinal and choriocapillaris in patients with multiple sclerosis: a 3-year study

OBJECTIVES

This study investigated the longitudinal progression of retinal structure and microvasculature over 3 years in patients with relapsing-remitting multiple sclerosis (RRMS) using optical coherence tomography (OCT) and OCT angiography (OCTA). It also explored the correlation between these changes and the Expanded Disability Status Scale (EDSS) scores.

METHODS

In this prospective, longitudinal study, we enrolled 66 patients with RRMS without history of optic neuritis and 124 healthy controls. All participants underwent full ophthalmological examination, OCT/OCTA scans, and disability scoring (EDSS) at baseline and after 12 and 24 months. OCT data were analyzed for retinal layer thickness, while OCTA assessed microvascular perfusion in the retinal capillary plexuses and choriocapillaris. Statistical models evaluated yearly rates of change and their association with EDSS scores.

RESULTS

The patients with RRMS exhibited 3.6 times faster thinning of the inner plexiform layer (IPL; - 0.47 µm per year, P = 0.001) compared to controls over 3 years. Additionally, superficial retinal capillary layer perfusion density decreased more rapidly at - 0.44% per year (P = 0.006) in patients with MS. A strong correlation was found between worsening EDSS scores and accelerated ONL thinning (estimated coefficient: - 1.62 µm/per unit change of EDSS score, P = 0.004).

DISCUSSION

This study demonstrates progressive retinal neurodegeneration and microvascular dysfunction in patients with RRMS without a history of optic neuritis. The association between ONL thinning and increased disability supports the potential of OCT/OCTA as valuable tools for monitoring disease progression and severity in RRMS.

Retinal small vessel pathology is associated with disease burden in multiple sclerosis

BACKGROUND

Alterations of the superficial retinal vasculature are commonly observed in multiple sclerosis (MS) and can be visualized through optical coherence tomography angiography (OCTA).

OBJECTIVES

This study aimed to examine changes in the retinal vasculature during MS and to integrate findings into current concepts of the underlying pathology.

METHODS

In this cross-sectional study, including 259 relapsing-remitting MS patients and 78 healthy controls, we analyzed OCTAs using deep-learning-based segmentation algorithm tools.

RESULTS

We identified a loss of small-sized vessels (diameter < 10 µm) in the superficial vascular complex in all MS eyes, irrespective of their optic neuritis (ON) history. This alteration was associated with MS disease burden and appears independent of retinal ganglion cell loss. In contrast, an observed reduction of medium-sized vessels (diameter 10-20 µm) was specific to eyes with a history of ON and was closely linked to ganglion cell atrophy.

CONCLUSION

These findings suggest distinct atrophy patterns in retinal vessels in patients with MS. Further studies are necessary to investigate retinal vessel alterations and their underlying pathology in MS.