Diffusion tensor imaging correlates of visual impairment in multiple sclerosis and chronic optic neuritis

Area of Science:

• Neuroscience
• Ophthalmology
• Radiology

Background:

• Multiple sclerosis (MS) and optic neuritis (ON) are demyelinating diseases affecting the visual system.
• White matter (WM) integrity is crucial for visual processing and function.
• Understanding the specific WM injury patterns in MS and ON is essential for diagnosing and managing vision loss.

Purpose of the Study:

• To compare white matter (WM) injuries associated with vision loss in multiple sclerosis (MS) and optic neuritis (ON).
• To investigate the relationship between visual impairment and WM damage in the primary visual pathway and whole brain.

Main Methods:

• Twenty-three MS patients with chronic unilateral ON and 14 healthy controls underwent visual acuity testing at varying contrast levels.
• Optical coherence tomography (OCT) assessed retinal nerve fiber layer (RNFL) thickness.
• Diffusion tensor imaging (DTI) evaluated WM integrity in the optic nerve, optic radiations, and whole brain.

Main Results:

• MS patients showed reduced RNFL thickness and altered optic nerve and radiation DTI measures compared to controls.
• In MS patients, reduced visual acuity in unaffected eyes correlated with WM injury in the optic nerve and radiations.
• Irrecoverable visual impairment in affected eyes correlated with WM injury in prefrontal and temporal regions, suggesting impaired visual processing remapping.

Conclusions:

• Visual impairment in unaffected eyes of MS patients is linked to WM injury within the visual pathway.
• Irrecoverable vision loss following ON is associated with damage to frontal WM, potentially hindering visual processing remapping.
• These findings highlight distinct WM injury patterns contributing to vision loss in MS and ON.