Visual pathway axonal loss in benign multiple sclerosis: a longitudinal study.

Area of Science:

• Neuroscience
• Ophthalmology
• Clinical Neurology

Background:

• Benign multiple sclerosis (MS) is traditionally characterized by mild neurological impairment (Expanded Disability Status Scale [EDSS] ≤3) and long disease duration (≥15 years).
• The extent of visual pathway axonal loss and its impact on vision and quality of life (QOL) in benign MS remain incompletely understood.

Purpose of the Study:

• To quantify retinal nerve fiber layer (RNFL) thickness, a marker of axonal loss, in patients with benign MS using optical coherence tomography (OCT).
• To assess visual function and QOL in benign MS patients and correlate findings with disease characteristics.

Main Methods:

• A longitudinal study analyzed data from patients with MS, including those with benign MS (EDSS ≤3, ≥15-year duration).
• Visual function was assessed using low- and high-contrast letter acuity.
• Retinal nerve fiber layer (RNFL) thickness was measured by time-domain OCT.
• Quality of life (QOL) was evaluated using the 25-Item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25) and the Short Form-36 Health Survey.

Main Results:

• Benign MS patients exhibited significant RNFL thinning comparable to typical MS patients.
• Both groups showed reduced low-contrast acuity, with benign MS patients reporting worse QOL scores (NEI-VFQ-25).
• A history of optic neuritis (ON) was more frequent in benign MS and correlated with RNFL thickness and disease duration, but not EDSS.

Conclusions:

• Patients with benign MS experience substantial axonal loss in the visual pathway, similar to typical MS.
• Despite mild overall disability, visual dysfunction significantly contributes to reduced vision and QOL in benign MS.
• The Expanded Disability Status Scale (EDSS) may not fully capture the extent of disability related to visual impairment in benign MS.