Abstract

A 79 year old Pakistanian male with complaints of nyctalopia and progressive decline of vision in both eyes was evaluated and found to exhibit the Mizuo-Nakamura phenomenon on fundoscopic examination. Dark adapted, bright flash ERG testing revealed a prominent negative waveform morphology. Fluorescein angiography and autofluorescent imaging were obtained and the results were consistent with a bulls eye maculopathy. Due to the patient’s subjective complaints of nyctalopia, the Mizuo-Nakamura phenomenon and the negative waveform ERG, a presumptive diagnosis of Oguchi’s disease was made. However, genetic testing failed to reveal mutations consistent with Oguchi’s disease and an alternative diagnosis was made. This case illustrates an interesting example of the Mizuo-Nakamura phenomenon associated with a negative ERG and reviews the various etiologies associated with these findings.