This finding together with the foveal thinning reported in NMO patients without optic neuritis (ON) history (Oertel et al., 2017; Yamamura and Nakashima, 2017), supports the concept of NMO to be a predominantly serum AQP4 IgG antibody-mediated astrocytopathy [NMO spectrum disorder (NMOSD)] that is distinct from MS (Wingerchuk et al., 2015). Here, AQP4 is linked to neuromyelitis optica.