Color vision is strongly associated with retinal thinning in multiple sclerosis.

OBJECTIVES Multiple Sclerosis (MS) frequently causes injury to the anterior visual pathway (AVP), impairing quality of life due to visual dysfunction. Development of biomarkers in MS is a high priority and both low-contrast visual acuity (LCVA) and time-domain optical coherence tomography (TD-OCT) have been proposed as candidates for this purpose. We sought to assess whether psychophysical assessments of color vision are similarly correlated with structural measures of AVP injury, and therefore augment measures of visual disability in MS. METHODS We studied the association between high-contrast visual acuity (HCVA), LCVA, color vision (Hardy-Rand-Rittler plates (HRR) and Lanthony D15 tests) and OCT, using both high-resolution spectral-domain OCT (SD-OCT; Spectralis, Heidelberg Engineering, Germany) and TD-OCT (Stratus, Carl Zeiss, US) in a cohort of 213 MS patients (52 with previous optic neuritis) and 47 matched controls in a cross-sectional study. RESULTS We found that MS patients have impairments in HCVA and LCVA (p < 0.001) but that they suffer from even more profound abnormalities in color discrimination (p < 0.0001). We found strong correlation between color vision and SD-OCT measures of retinal nerve fiber layer (RNFL) thickness (average RNFL, r = 0.594, p < 0.001) and papillomacular bundle thickness (r = -0.565, p < 0.001). The correlation between OCT scores and functional visual impairments of all types was much stronger for SD-OCT than for TD-OCT. CONCLUSION Our results indicate that color vision is highly correlated with these OCT scores when compared with traditional measures of visual acuity. Also we found that SD-OCT is superior to TD-OCT for detecting anterior visual pathway damage in MS. This makes both color-visual measures and SD-OCT strong candidate biomarkers of disease progression.