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

ABSTRACT

Abnormalities of the inner and intermediate retinal structures in patients with amyotrophic lateral sclerosis (ALS) have been described using optical coherence tomography and histopathology. Colour vision is a potential marker of these structural changes. The purpose of this study is to test the hypothesis that colour vision impairment is associated with ALS. Monocular (right eye) colour vision was assessed in subjects with definite or probable ALS (n = 25, aged 50–80 years) and control (n = 21, aged 46–89 years) subjects with corrected near visual acuity of at least 20/40 using the L’Anthony D15 color test (desaturated), scored by c-index, a measure of diffuse colour discrimination. Of ALS subjects, 16/25 (64%) had impaired colour vision (c-index >1.8). Comparing with our normal subjects and accounting for age, 72% (n = 18) of ALS subjects had colour vision below the 50th percentile, 52% (n = 13) had colour vision below the 25th percentile, 24% (n = 6) had colour vision below the 10th percentile, and 8% (n = 2) had colour vision below the 2nd percentile. In multivariate models of ln(c-index) and age, the intercept was higher and the slope was flatter in ALS subjects, suggesting that colour vision deficits are more prominent in younger ALS patients. Diffuse colour discrimination deficits are detected in ALS subjects at younger ages than in control subjects. Further study is needed to confirm these findings and to determine if the ALS colour discrimination abnormalities correlate with structural markers of retinal involvement and ALS disease severity.

KEYWORDS:

• Amyotrophic lateral sclerosis
• colour vision
• desaturated L’Anthony D-15
• retinal disease

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Funding

This work was supported by National Institutes of Health grants K23 EY024345 and K12 EY02147; Research to Prevent Blindness Unrestricted Grant to the University of Illinois at Chicago Department of Ophthalmology; and Research to Prevent Blindness Unrestricted Grant to the Stanford Department of Ophthalmology.

Additional information

Funding

This work was supported by National Institutes of Health grants K23 EY024345 and K12 EY02147; Research to Prevent Blindness Unrestricted Grant to the University of Illinois at Chicago Department of Ophthalmology; and Research to Prevent Blindness Unrestricted Grant to the Stanford Department of Ophthalmology.