Role of VEPS and OCT in demyelinating diseases

The visual pathways offer a unique platform for integrated assessment of demyelinating, neurodegenerative and repair mechanisms in demyelinating diseases. While visual evoked potentials (VEPs) allow to assess the functional impact of a demyelinating lesion, optical coherence tomography measures in vivo the neuroaxonal and inflammatory processes, based upon microstructural changes in the different retinal layers. After optic neuritis, the combination of the two methods may assist in the differential diagnosis between multiple sclerosis (MS), characterized by autoimmune processes mainly targeting myelin, from neuromyelitis optica spectrum disorder, characterized by a more severe neuroaxonal damage. As VEPs become abnormal very early during development of optic neuritis symptoms, while OCT reveals neuroaxonal damage, we should refine the appropriate time sequencing of both methods when integrating them in clinical practice, observational research and clinical trials. Concerning the latter application, these methods provide useful measures for treatment interventions targeting remyelination (VEPs) and neuroprotection (OCT). Finally, the study of eyes not affected by optic neuritis in MS and NMOSD provides useful measures of hidden underlying processes associated with disease activity, compartimentalized inflammation and neurodegeneration, which are also an important target of different therapeutic interventions.