Mizuo phenomenon seen in (AIIMS Nov 2011)
(REF:Kanskii clinical ophthalmology sixth edition pg 683)
1. The most interesting feature of this disease is the reversal of all the features described above, if the patient sits in the dark for about one hour. This is called Mizuo's Nakamura phenomenon.
2. The retina looks normal and the night-blindness disappears. After the fundus has resumed the normal colour, exposure to room light soon leads to the appearance of fundus discolouration.