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A. Berezovsky, E. P. Andrade, P. Y. Sacai, S. R. Salomao; Subclinical Visual Abnormalities Assessed by Visual Evoked Potential in Clinically Definite Multiple Sclerosis. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3303.
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© ARVO (1962-2015); The Authors (2016-present)
Visual dysfunction is a common finding in multiple sclerosis (MS), a chronic inflammatory disease of the central nervous system. Visual evoked potential (VEP) has been widely used to evaluate visual pathways in MS. The purpose of this study was to assess pattern-reversal VEP (PRVEP) in patients with clinically definite MS with and without visual acuity deficit.
A group of 24 patients (20 females), aging from 16 to 60 years (mean=40.2 ± 10.7) with clinically definite MS diagnosis based on MRI, liquor and neurologic assessment was retrospectively studied. Transient PRVEP (reversal rate = 2Hz; checkerboard stimuli 15’ and 60’; 100% contrast) was obtained under monocular stimulation. PRVEP recording followed ISCEV clinical protocol. P100 latency (ms) and N75-P100 amplitude (µV) were determined for both stimulus sizes. Inter-ocular asymmetries for both amplitude (≥30%) and latency (≥3.5ms) were determined. Monocular visual acuity was measured using a retro-illuminated ETDRS tumbling E chart for distance with optical correction when needed.
P100 prolonged latency for one or both stimulus sizes were found in 13 (54%) patients, with non-recordable PRVEPs in 2 (8%) patients and normal PR-VEPs for both N75-P100 amplitude and latency in 9 (38%) patients. Inter-ocular differences for latency and amplitude were found respectively in 11 (46%) and 6 (25%) patients. Out of 13 patients with prolonged P100 latency, 9 had visual acuity ≥ 20/25 in either eye and 6 had reduced N75-P100 amplitude for one or both stimulus sizes. There was a significant correlation between P100 latency and better acuity eye (logMAR) for both 60’ (r=0.85; p<0.0001) and 15’ (r=0.87; p<0.0001) stimulus sizes. No correlation was found between N75-P100 amplitude and visual acuity.
One third of clinically definite MS patients showed normal visual acuity along with prolonged latency and/or reduced amplitude in PRVEP. These findings are consistent with primary demyelination with relative preservation of axons and confirm that VEP is a sensitive tool for revealing subclinical visual pathways abnormalities in patients with MS.
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