Independent patterns of damage to retinocortical pathways in multiple sclerosis without a previous episode of optic neuritis

Abstract

Asymptomatic visual loss is a feature of multiple sclerosis (MS) but its relative impact on distinct retinocortical pathways is still unclear. The goal of this work was to investigate patterns of subclinical visual impairment in patients with MS with and without clinically associated previous optic neuritis (ON). We have used functional methods that assess parvo-, konio- and magnocellular pathways in order to compare pathophysiological mechanisms of damage in a population of 44 subjects with MS (87 eyes), with and without a previous episode of ON. These methods included chromatic contrast sensitivity across multiple chromatic axes (Cambridge Colour Test-parvo/konio pathways), perimetric achromatic contrast sensitivity for the magno pathway [frequency doubling technique (FDT)] and pattern visual evoked potentials (VEP). These measures were correlated with field sensitivity measures obtained using conventional automated static perimetry (ASP) and were also compared with conventional clinical chromatic/achromatic contrast sensitivity chart-based measures. We have found evidence for uncorrelated damage of all retinocortical pathways only in patients with MS without ON. VEP evidence for axonal damage was found in this group supporting the emerging notion of axonal damage even in sub-clinical stages of ON/MS pathophysiology. Only in this group was significant correlation of functional measures with disease stage observed, suggesting that distinct pathophysiological milestones are present before and after ON has occurred.

Aging of Low and High Level Vision: From Chromatic and Achromatic Contrast Sensitivity to Local and 3D Object Motion Perception

“…On the other hand, local speed signals are mainly processed in early human visual cortex, in particular V1 and V2 [41]. Finally, chromatic and achromatic contrast sensitivity tests require the integrity of low-level retinal or retinocortical visual pathways [28], [31], [42]. Direct comparisons of performance in these tasks that differentially require low- and high-level visual processing can therefore help inferring on how distinct neural pathways are affected by the aging process.…”

Neuroretinal Dysfunction With Intact Blood-Retinal Barrier and Absent Vasculopathy in Type 1 Diabetes

“…Far vision refractive correction was worn by participants, and tinted contact/spectacle lenses were replaced by lenses in a trial frame when necessary. The test ended after 11 reversals of each adaptive staircase, and the mean of the last 7 reversals was obtained as the threshold expressed in confusion vector length for each protan, deutan, and tritan axes in CIE 1976 u'v' color space units (32,33).…”

“…Achromatic contrast sensitivity within the magnocellular pathway was probed using a perimetric test based on frequency-doubling technology (FDT) (33)(34)(35). Vertically oriented sinusoidal grating stimuli (0.25 cpd, 25 Hz) were presented monocularly using a Humphrey Matrix Perimeter (Carl Zeiss Meditec Inc.).…”

Progress in multiple sclerosis research in the last year

“…Zaaraoui et al [17] demonstrated, by using magnetic resonance spectroscopic examinations, that the occurrence of neural dysfunction during the first 5 years of MS is associated with cognitive deterioration. Reis et al [18] found evidence of uncorrelated damage of all retinocortical pathways only in MS patients without optic neuritis (ON), supporting the notion of axonal damage even in subclinical stages of ON/MS pathophysiology.…”