What makes the acute optic neuritis model unique in an era of trials for neuroprotective and myelin repair agents? Acute optic neuritis (AON) is a common,and often the earliest manifestation of central nervous system (CNS) inflammatory demyelinating disorders like multiple sclerosis (MS) and neuromyelitis optica (NMO).It affects at least half the patients with MS and is the presenting feature in 15-20％ of patients.Vision loss in AON secondary to NMO tends to be more severe with less potential for recovery and greater axonal degeneration,as measured by optical coherence tomography (OCT) (Bennett et al.,2014).Several unique features of the afferent visual pathway (AVP) make the AON model an ideal system to study disease pathogenesis and evaluate potential neuroprotective and myelin repair strategies.