Visual function resists early neurodegeneration in the visual system in primary progressive multiple sclerosis.

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Multiple sclerosis (MS) neurodegeneration impacts the visual system.
• Pathomechanisms and long-term dynamics in primary progressive MS (PPMS) remain unclear.

Purpose of the Study:

• To assess longitudinal changes in visual function and retinal neurodegeneration in PPMS.
• To investigate correlations between visual outcomes, MRI, and serum NfL (sNfL) levels.

Main Methods:

• Prospective study of 81 PPMS patients and healthy controls over 2.7 years.
• Assessed visual function (AULCSF), retinal nerve fibre layer thickness (RNFL) via OCT, MRI, and sNfL.
• Correlated changes over time and with disease progression.

Main Results:

• PPMS patients showed reduced RNFL compared to controls.
• Visual function (AULCSF) remained stable despite RNFL loss until a turning point.
• AULCSF progression correlated with increased Expanded Disability Status Scale scores.
• sNfL levels were elevated but stable and not associated with visual outcomes.

Conclusions:

• Neurodegeneration in the anterior visual system precedes functional impairment in PPMS.
• Visual function is maintained until a specific threshold of neurodegeneration is reached.
• sNfL is not a reliable biomarker for structural or functional visual system damage in PPMS.