Usefulness of optical coherence tomography to distinguish optic neuritis associated with AQP4 or MOG in neuromyelitis optica spectrum disorders

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory central nervous system disease that preferentially affects the optic nerve and spinal cord [Wingerchuk et al. 2015]. Up to 70% of patients with NMOSD have antibodies to aquaporin-4 (AQP4-IgG). AQP4 is expressed in astrocytes of the optic nerve and Muller cells in the eye. A subgroup of AQP4-IgG-seronegative patients has antibodies to myelin oligodendrocyte glycoprotein (MOG-IgG), and optic neuritis (ON) relapses are also frequent in these patients [Hoftberger et al. 2015].We hypothesize that retinal injury may be additionally driven by Muller cells dysfunction in patients with AQP4-IgG. This condition, in contrast with those patients who harbour MOG-IgG, may induce differential changes in the outer retinal layers. In this brief series of cases, we aim to investigate if optical coherence tomography (OCT) may distinguish ON associated with AQP4-IgG or MOG-IgG in NMOSD.