Mizuo-Nakamura Phenomena.

A 21-year-old male presented with a chief complaint of night blindness since early childhood. The patient had no history of hemeralopia or photophobia, and no family history of such illness or use of glasses. On examination, his visual acuity was 6/6 in both eyes. Pupils were reacting normally. Dilated fundus examination revealed diffuse golden-yellow sheen throughout the fundus with prominent retinal vasculature, but arteries and veins were less distinguishable. Choroidal vessels were not visible. The patient was then patched and dark adapted for 6 hours. The dark-adapted fundus showed the disappearance of the golden sheen with normal visible choroidal and retinal vasculature. This characteristic phenomenon observed on fundus examination from dark-adapted state to light adaptation is known as Mizuo-Nakamura phenomenon. Although this phenomenon is classical of Oguchi disease, it is also seen in X-linked cone dystrophy and X-linked retinoschisis. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:1068.].