Evaluation of the visual system in multiple sclerosis. II. Colour vision

Area of Science:

• Ophthalmology
• Neurology
• Vision Science

Background:

• Multiple sclerosis (MS) is a neurological condition affecting the central nervous system.
• Optic neuritis is a common early symptom of MS, often impacting visual function.
• Color vision (CV) deficits can be an early indicator of optic nerve damage in MS.

Purpose of the Study:

• To evaluate and compare the sensitivity of different color vision tests in detecting visual pathway damage in MS patients.
• To correlate color vision test results with pattern-reversal visual evoked potentials (PR-VEP) findings.
• To assess the reproducibility and potential improvements for the Ishihara (I-test) in MS diagnosis.

Main Methods:

• A cohort of 65 MS patients (30 with prior optic neuritis) and 51 controls underwent color vision testing using Ishihara's pseudoisochromatic plates (I-test), Farnsworth's panel D-15 test (F-test), and Lanthony's desaturated 15-hue test (L-test).
• Error scoring was performed using Bowman's computerized method and a proposed simpler scoring system.
• Results were compared with pattern-reversal visual evoked potentials (PR-VEP) data.

Main Results:

• The Ishihara (I-test) identified abnormalities in 56% of eyes, showing higher sensitivity to demyelination than the Lanthony (47%) and Farnsworth (26%) tests.
• Pattern-reversal VEPs were abnormal in 80% of eyes.
• Blue-yellow color vision defects were most common, occurring even in patients with normal VEP latencies.

Conclusions:

• The Ishihara (I-test) is a sensitive and reproducible tool for detecting color vision deficits in multiple sclerosis.
• Color vision testing, particularly with the Ishihara test, can reveal visual pathway damage not always evident with VEPs.
• Enhancements to the Ishihara test, such as additional blue-yellow plates, could further improve its diagnostic utility in MS.