Abstract
Purpose::
The goal of this work was to evaluate and quantify subtle visual dysfunction in multiple sclerosis (MS) with or without associated Optic Neuritis (ON) to correlate novel functional markers with classical clinical parameters.
Methods::
Conventional and novel computerized psychophysical assessment methods were used to evaluate visual function in a population of 47 subjects (94 eyes) with MS: Colour Vision Tests (using Ishihara plates, IF-2 Anomaloscope and the Cambridge Colour Test - CCT), Contrast Sensitivity Methods (Vistech and Frequency Doubling Technology) and Automated Static Perimetry. We have also measured VEPs (Visual Evoked Potentials) in order to evaluate objectively the effect of demyelination on bioelectrical conduction along the optic pathway. Statistical analysis was performed using ANOVA at a significance level of p< 0.05.
Results::
Interestingly, using CCT, we have found evidence for damage of all cone pathways in MS, even in the absence of ON. Achromatic contrast sensitivity within the magnocellular pathway (FDT) showed impairment for global parameters (MD and PSD) and for five different locations (central area, and superior temporal, superior nasal, inferior temporal and inferior nasal quadrants). Again, impairment could be detected in MS without ON. VEP results showed also a very good sensitivity to subtle damage, revealing nervous conduction delay even in cases of MS with no clinical signs of ON. Amplitude analysis was less revealing. Correlation analysis showed that CCT is very sensitive in damage detection even in patients with high visual acuity.
Conclusions::
Novel computed psychophysical and electrophysiological methods are good quantitative markers of damage to central and peripheral pathways induced by ON and may provide new valuable tools to understand the physiopathology of MS.
Keywords: visual impairment: neuro-ophthalmological disease • color vision • electrophysiology: clinical