Original articleCorrelation between functional and structural assessments of the optic nerve and retina in multiple sclerosis patientsCorrélation entre l’évaluation fonctionnelle et structurelle du nerf optique et de la rétine des patients atteints de sclérose en plaques
Introduction
Visual evoked potentials (VEP) may be delayed in patients with Multiple Sclerosis (MS) [3], [24], [26], [34]. The pattern electroretinogram (PERG) also displays early abnormalities in MS patients, mainly in the N95 component [10], [11], [13]. Although the exact PERG generators have yet to be fully elucidated, current evidence suggests that the N95 component of the PERG is a contrast-related component generated in relation to retinal ganglion cell function, while the P50 component is partly ganglion cell-derived, though with a contribution from structures distal to the ganglion cells in the visual pathways [14].
Since axonal damage is considered to give rise to progressive disability in MS [20], some authors have searched for a reliable tool to quantify it [17], [19]. Ganglion cell axons, which are a part of the CNS, are commonly affected in MS, not only in eyes with a prior episode of optic neuritis, but also in eyes with no known prior episode [4], [5], [7], [8], [32]. Since this layer lacks myelin, structural evaluation of the retinal nerve fiber layer (RNFL) has been proposed as a useful biomarker of MS activity [15], [28].
There is little available evidence concerning the existence of any correlations between morphological evaluations (using Optical coherence tomography (OCT) and/or Scanning laser polarimetry, GDx) and neurophysiological evaluations (VEPs or PERG) of the optic nerve [32], [23]. The aim of this study was to evaluate not only the performance of VEPs, PERG, OCT and GDx in the same MS sample population, but also to determine if there is any correlation between these methods of functional and structural assessments of the optic nerve.
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Patients
Nineteen patients with definite multiple sclerosis (MS group) and 19 sex- and age-matched controls were enrolled in the study. The mean ages of the MS patients were 42.9 years (range 38.4–47.3), and 47.0 years (range 42.6–51.3), respectively. The local ethics committee approved the research protocol, which adhered to the tenets of the Declaration of Helsinki. All participants provided written informed consent.
MS was diagnosed by standard clinical and neuroimaging criteria [27]. The following
Results
We studied 76 eyes from 19 patients with definite MS and 19 age-and sex-matched healthy controls (both eyes from each patient were included). Since we evaluated age- and sex-matched healthy subjects, no differences were observed in these descriptive characteristics between MS patients and controls (Table 1).
Comparisons between VEP/PERG results and structural parameters were performed in both healthy and MS eyes, irrespective of whether they had a history of optic neuritis or not (Table 2). The
Discussion
Multiple sclerosis is an immune-mediated demyelinating and neurodegenerative disease of the central nervous system. Both the evidence that axonal damage occurs in multiple sclerosis and its relationship with permanent disability have been previously described [17], [18], [31]. Some recent models support the presence of two connected mechanisms that take place in MS: inflammation and neurodegeneration. However, the temporal relationship between both remains unclear [9].
The retina is a good model
Conflicts of interest
The authors have not declared any conflict of interest.
References (34)
- et al.
Pattern electroretinography and visual evoked potentials in optic nerve diseases
J Clin Neurosci
(2006) - et al.
Recommended standards for electroretinograms and visual evoked potentials. Report of an IFCN committee
Electroencephalogr Clin Neurophysiol
(1993) - et al.
Optical coherence tomography in multiple sclerosis
Lancet Neurol
(2006) - et al.
The neuroprotective effect of inflammation: implications for the therapy of multiple sclerosis
J Neuroimmunol
(2000) The pattern electroretinogram and an integrated approach to visual pathway diagnosis
Prog Retin Eye
(2001)The incidence of anormal pattern electroretinography in optic nerve demyelination
Electroencephalogr Clin Neurophysiol
(1991)- et al.
Optical coherence tomography to detect and manage retinal disease and glaucoma
Am J Ophthalmol
(2004) - et al.
Impaired VEP after photostress in multiple sclerosis patients previously affected by optic neuritis
Electroencephalogr Clin Neurophysiol
(1998) - et al.
Scanning laser polarimetry to measure the nerve fiber layer of normal and glaucomatous eyes
Am J Ophthalmol
(1995) - et al.
Conventional perimetry, short-wavelength automated perimetry, frequency-doubling technology, and visual evoked potentials in the assessment of patients with multiple sclerosis
Eur J Ophthalmol
(2005)