Orientational contrast sensitivity and chromatic contrast thresholds in multiple sclerosis

Area of Science:

• Ophthalmology
• Neuroscience
• Visual Science

Background:

• Multiple Sclerosis (MS) is a demyelinating disease affecting the central nervous system.
• Visual pathway involvement is common in MS, but often assessed with standard visual acuity (VA).
• Subtle visual processing deficits may precede or occur independently of VA reduction.

Purpose of the Study:

• To investigate abnormalities in orientational contrast sensitivity (CS) and chromatic contrast threshold (CCT) in multiple sclerosis (MS).
• To assess visual function in MS patients with preserved visual acuity.
• To utilize a computerized psychophysical approach for precise measurement.

Main Methods:

• A case-control study comparing 9 MS patients (Expanded Disability Status Scale ≤3, logMAR VA < 0.1) with 20 age-matched controls.
• Measurement of achromatic CS at various spatial frequencies (horizontal and vertical orientations) and CCT along red-green and tritan axes using a high-resolution monitor.
• A randomized double-staircase reversal algorithm was employed for threshold determination.

Main Results:

• Two MS subjects exhibited loss in both horizontal and vertical CS; three had isolated vertical CS loss.
• Significant reductions in red-green and tritan discrimination thresholds were observed in MS patients compared to controls (P = .016 for both).
• These visual deficits occurred in the absence of reduced visual acuity.

Conclusions:

• Computerized psychophysical testing offers a reliable method to detect visual abnormalities in MS.
• Confirms that MS is associated with potential loss of orientational CS and color vision.
• Highlights the importance of assessing specialized visual functions in MS management, even with normal VA.