# Optical Coherence Tomography Changes in Central Nervous System Inflammatory Demyelinating Diseases: A Longitudinal Retrospective Study

## TL;DR

This study uses OCT to track retinal changes in different types of central nervous system inflammatory demyelinating diseases over one year, showing progressive degeneration.

## Contribution

The study provides longitudinal OCT data across multiple CNS-IDD subgroups, highlighting OCT's potential as a biomarker for disease monitoring.

## Key findings

- NMOSD and SPMS showed the most significant retinal degeneration over 12 months.
- CIS patients had the best baseline and maintained relative preservation over time.
- Optic disc swelling increased in all groups, especially in SPMS, NMOSD, and MOGAD.

## Abstract

Background

Optical coherence tomography (OCT) is considered an indispensable, non-invasive imaging modality that provides insights into neuroaxonal integrity in several retinal and optic nerve disorders by offering high-resolution, cross-sectional visualization of retinal and optic nerve head layers. With its capability of providing imaging of retinal microstructures, recently, OCT has been used in the assessment of central nervous system inflammatory demyelinating diseases (CNS-IDDs). These diseases, such as clinically isolated syndrome (CIS), relapsing-remitting multiple sclerosis (RRMS), secondary progressive multiple sclerosis (SPMS), neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), are frequently associated with visual pathway impairment. Our purpose in this research is to evaluate longitudinal OCT changes and visual function across CNS-IDD subgroups.

Methods

This is a retrospective cohort study including 80 patients with CNS-IDDs (10 CIS, 30 RRMS, 20 SPMS, 10 NMOSD, 10 MOGAD) who underwent OCT at baseline, 3, 6, 9, and 12 months at the Ophthalmology department at King Hussein Medical Center. All patients received a detailed ophthalmic assessment, including measuring visual acuity (VA) using the Snellen chart under standard illumination, performing OCT to measure both ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (pRNFL). The optic nerve head was assessed to determine the presence or absence of swelling using dilated fundoscopy and optic nerve head photos. Optic disc swelling was recorded as a categorical variable. Longitudinal and subgroup comparisons were analyzed using repeated-measures GLM and Bonferroni-adjusted post hoc tests.

Results

At baseline, CIS patients showed the most favorable parameters (VA 0.05 ± 0.008 LogMAR; GCIPL 85.06 ± 0.43 µm; pRNFL 97.00 ± 0.36 µm), while NMOSD exhibited the poorest outcomes. Over 12 months, all groups showed a continued decline of VA and thinning of GCIPL and pRNFL (p < 0.001). Optic disc swelling increased from 50.0% at baseline to 76.3% at 12 months, eventually affecting all SPMS, NMOSD, and MOGAD patients. Pairwise analyses confirmed significant subgroup differences, with NMOSD consistently demonstrating the worst structural and functional outcomes.

Statistical analysis revealed significant longitudinal reductions in VA, GCIPL, and pRNFL thickness across all subgroups (p < 0.001). Between-group comparisons showed significant differences for baseline and 12-month values (CIS vs NMOSD, p < 0.001; RRMS vs SPMS, p = 0.02; MOGAD vs SPMS, p = 0.04). Changes over time within each diagnostic category also reached statistical significance (all p < 0.001 by repeated-measures GLM).

Conclusion

OCT clearly showed a pattern of progressive neuroretinal degeneration across all CNS-IDD subgroups. The most significant changes were detected in NMOSD and SPMS, whereas CIS showed relative preservation, highlighting the potential role of OCT in monitoring disease course and differentiating phenotypes. Our findings emphasize the clinical value of OCT as a sensitive, non-invasive, reliable biomarker of visual pathway changes in CNS demyelinating diseases.