Diffuse Colour Discrimination as Marker of Afferent Visual System Dysfunction in Amyotrophic Lateral Sclerosis

Area of Science:

• Ophthalmology
• Neurology

Background:

• Retinal structural abnormalities in amyotrophic lateral sclerosis (ALS) are documented via optical coherence tomography and histopathology.
• Color vision serves as a potential indicator of these retinal structural changes.

Purpose of the Study:

• To investigate the association between color vision impairment and amyotrophic lateral sclerosis (ALS).
• To test the hypothesis that ALS patients exhibit color vision deficits.

Main Methods:

• Assessed monocular color vision in 25 ALS patients (aged 50-80) and 21 controls (aged 46-89) using the L'Anthony D15 desaturated color test.
• Quantified color discrimination using the c-index, comparing ALS subjects to normative data and accounting for age in multivariate models.

Main Results:

• 64% (16/25) of ALS subjects demonstrated impaired color vision (c-index >1.8).
• When compared to controls and adjusted for age, 72% of ALS subjects fell below the 50th percentile for color vision.
• Multivariate analysis indicated that color vision deficits are more pronounced in younger ALS patients, with a flatter age-related slope.

Conclusions:

• Diffuse color discrimination deficits are detectable in ALS patients at earlier ages compared to control subjects.
• Further research is warranted to confirm these findings.
• Future studies should explore correlations between ALS-related color vision abnormalities, retinal structural markers, and disease severity.