Abstract
Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease of the central nervous system, characterized by demyelination, axonal dysfunction, and neuronal degeneration. The anterior visual pathway is often affected. 30% to 70% of patients diagnosed with MS will have optic neuritis (ON) during the course of the disease (1); visual problems are frequently the earliest symptoms. Asymptomatic or subclinical involvement of optic nerves occurs in MS as well. Common noninvasive tests to evaluate visual pathway abnormalities include a subjective test of visual sensitivity, standard automated perimetry, and structural evaluations of retina and retinal nerve fiber layer integrity, using optical coherence tomography or other imaging approaches. This talk will summarize recent work evaluating the relative utility of two objective electrodiagnostic tests, multifocal visual evoked potential (mfVEP) and photopic electroretinogram (ERG), in assessing visual function in MS/ON eyes and in MS eyes without a history of ON. The mfVEP technique, which records 60 local visual evoked responses simultaneously from a 40 deg field of vision provides amplitude measures reflecting neuronal function, and also, uniquely, information about nerve conduction velocity (latency) which is useful for assessing extent of demyelination. The mfVEP technique has high sensitivity and specificity in detecting visual pathway abnormalities in patients with MS/ON, and is also useful in detecting subclinical lesions. The amplitude of the photopic negative response (PhNR) of the photopic ERG provides information on the function of retinal ganglion cells and their axons, within the eye. The PhNR amplitude reductions in eyes of MS patients both with and without a history of ON indicate the presence, in the retina, of subclinical pathologic changes associated with the disease.
Meeting abstract presented at OSA Fall Vision 2012