Color vision impairment in multiple sclerosis points to retinal ganglion cell damage

Abstract

Multiple Sclerosis (MS) results in color vision impairment regardless of optic neuritis (ON). The exact location of injury remains undefined. The objective of this study is to identify the region leading to dyschromatopsia in MS patients' NON-eyes. We evaluated Spearman correlations between color vision and measures of different regions in the afferent visual pathway in 106 MS patients. Regions with significant correlations were included in logistic regression models to assess their independent role in dyschromatopsia. We evaluated color vision with Hardy-Rand-Rittler plates and retinal damage using Optical Coherence Tomography. We ran SIENAX to measure Normalized Brain Parenchymal Volume (NBPV), FIRST for thalamus volume and Freesurfer for visual cortex areas. We found moderate, significant correlations between color vision and macular retinal nerve fiber layer (rho = 0.289, p = 0.003), ganglion cell complex (GCC = GCIP) (rho = 0.353, p < 0.001), thalamus (rho = 0.361, p < 0.001), and lesion volume within the optic radiations (rho = -0.230, p = 0.030). Only GCC thickness remained significant (p = 0.023) in the logistic regression model. In the final model including lesion load and NBPV as markers of diffuse neuroaxonal damage, GCC remained associated with dyschromatopsia [OR = 0.88 95 % CI (0.80-0.97) p = 0.016]. This association remained significant when we also added sex, age, and disease duration as covariates in the regression model. Dyschromatopsia in NON-eyes is due to damage of retinal ganglion cells (RGC) in MS. Color vision can serve as a marker of RGC damage in MS.

Visual dysfunction and its correlation with retinal changes in patients with Alzheimer's disease

“…The loss of RGC was recently identified as the ultimate responsible for visual impairment in patients suffering from another neurodegenerative process, multiple sclerosis. 33 Thus, a similar process could be the cause of contrast and color deficiencies in AD individuals.…”

Optical coherence tomography in multiple sclerosis

“…Many studies have found correlations between the thickness of the GCIPL and the RNFL, and visual acuity, especially low contrast visual acuity [14][15][16]. One study also detected a moderate, statistically significant correlation between dyschromatopsia and GCIPL thickness in MS-NON eyes [17].…”

“…MRI studies have found several associations between RNFL thickness and MRI parameters in MS patients [27][28][29][30]. Furthermore, recent studies have observed correlations between GCIPL thickness and thalamus volume [31], normalized brain parenchymal volume [17], intracranial volume [22], cortical grey matter volume [22], and number and volume of cortical lesions [31]. Additionally, studies have found associations between increased thinning of the GCIPL and T2 lesions [26], increased lesion volume in the optic radiation [32] and development of contrast-enhancing lesions [26,27].…”

Visual dysfunction and its correlation with retinal changes in patients with Parkinson's disease: an observational cross-sectional study

“… 23 RGC loss (as observed using SD-OCT) was recently identified as the cause of visual impairment in patients suffering from another neurodegenerative process, multiple sclerosis. 24 Thus, a similar process could be the cause of the contrast and colour deficiencies in patients with PD. In addition, in the mammalian retina, colour vision and contrast sensitivity are modulated through D1 and D2 receptors.…”