Muller Cell Function in Neuromyelitis Optica as Measured by Electrophysiologic Testing

Neuromyelitis optica (NMO) is an inflammatory demyelinating disorder of the central nervous system [1]. Antibodies against the astrocyte water channel protein aquaporin 4 (AQP4) have been implicated in the pathogenesis of NMO [2]. AQP4 has been found in the optic nerve as well as on Muller cells in the retina [3,4]. Patients who develop NMOassociated optic neuritis have a poorer prognosis for recovery with greater loss of retinal ganglion cell axons [5]. It is unclear if the visual prognosis in NMO is secondary to damage to the optic nerve alone or in combination with damage to Muller cells with subsequent retinal dysfunction. Intact Muller cell function may be reflected by a positive B-wave duringERG testing. This study was designed to evaluate the function of Muller cells as measured by electroretinography (ERG) testing in NMO patients.