The International Society for Clinical Electrophysiology of Vision protocol was used to record the ERGs. The scotopic ERGs after 30 minutes of dark adaptation showed slightly reduced amplitude and delayed implicit time in b-wave (Figure, C). The bright-flash ERG (30 candelas·seconds/m2) had a positive configuration, although the b:a ratio was lower than normal (Figure, C). The photopic and flicker ERGs performed after 10 minutes of light adaptation were normal (Figure, C). To determine the extent of the rod function recovery, bright-flash ERGs were recorded 4 times at 30-second intervals after 30 minutes of dark adaptation. During the 4 stimuli, the waveform changed from the positive pattern to a negative configuration with a severely reduced b-wave and additional milder reduction of the a-wave, which is characteristic of homozygous Oguchi disease (Figure, D). To our knowledge, this phenomenon has never been reported in normal eyes, in eyes with the typical type of Oguchi disease, or in other cases of Oguchi disease with the same heterozygous SAG mutation (Figure, D). The superimposed ERGs elicited by the 4 consecutive flashes show the variation of rod function recovery (Figure, E).