Pathophysiological basis of low contrast visual acuity loss in multiple sclerosis

Area of Science:

• Neuroscience
• Ophthalmology
• Clinical Biomarkers

Background:

• Multiple Sclerosis (MS) requires reliable biomarkers for remyelination trials.
• Low Contrast Visual Acuity (LCVA) is a potential functional measure of visual pathway integrity.

Purpose of the Study:

• To determine the roles of axonal loss and demyelination in MS patients' LCVA loss.
• To evaluate LCVA as a biomarker for remyelination therapies.

Main Methods:

• 50 relapsing-remitting MS patients with prior optic neuritis were studied.
• Linear regression analyzed multifocal Visual Evoked Potential (mfVEP) latency and Retinal Nerve Fiber Layer (RNFL) thickness in relation to LCVA.

Main Results:

• Intereye asymmetry in mfVEP latency and RNFL thickness correlated with LCVA asymmetry (P < 0.001).
• Combined mfVEP latency and RNFL thinning predicted LCVA (R² = 0.67), with RNFL thinning being a stronger predictor.
• Excluding severe axonal loss increased mfVEP latency's contribution, diminishing RNFL's significance.

Conclusions:

• Retinal ganglion cell axonal loss is the primary LCVA predictor.
• Demyelination significantly contributes to LCVA reduction, particularly in milder cases.
• LCVA is a feasible biomarker for remyelination trials with careful patient selection.