Optic Nerve Head Component: A Potential New Metric for Optic Neuritis

Jeffrey L. Bennett, MD, PhD

An electrophysiologic metric of optic nerve function may facilitate our understanding of CNS demyelination and expedite the development of new therapies.

Optic neuritis (ON) is the most common presentation of multiple sclerosis (MS) and a prototypic example of acute demyelinating injury. Advances in retinal imaging and electrophysiology have allowed ON to serve as a unique clinical model for evaluating acute central nervous system demyelination by providing accurate measures of the anatomic and functional consequences of acute ON. The optic nerve head component (ONHC) response is an electrophysiologic correlate of the multifocal electroretinogram that signifies a change from membranous (unmyelinated) to saltatory (myelinated) conduction in healthy people. Therefore, abnormalities in the ONHC may provide a sensitive metric for the severity of injury following acute ON.

In this pilot investigation, the researchers characterized ONHC responses from 10 normal subjects and 7 patients with MS. The number of abnormal or absent ONHC responses was significantly different between MS eyes and healthy eyes. Surprisingly, the number of abnormal ONHC responses was not significantly different between MS eyes with and without a history of acute ON. A detailed structure-function analysis in a single MS patient demonstrated that the number and distribution of abnormal ONHC responses correlated with low-contrast acuity, visual-field loss, and retinal nerve fiber layer thinning.

Citation(s):

Frohman TC et al. Optic nerve head component responses of the multifocal electroretinogram in MS. Neurology 2013 Aug 6; 81:545.