Incomplete congenital stationary night blindness: electroretinogram c-wave and electrooculogram light rise

Three cases of congenital stationary night blindness are reported. In all patients a negative electroretinogram was recorded by single bright flash stimulation and changed to positive on sequential reduction of the stimulus intensities. Oscillatory potentials were recognized. Biphasic dark adaptation curves and moderate elevation of the relative logarithmic final threshold of dark adaptation were also found. Values of critical flicker fusion frequency were reduced to a mild or moderate extent. VEP latency was prolonged beyond the normal range in two cases. In all three the electroretinogram c-wave was extinguished despite a normal electrooculogram light-dark ratio. It is hypothesized that in congenital stationary night blindness some disorder may exist in the apical membrane of the retinal pigment epithelium but not in the basal membrane in view of dissociation between the c-wave response and the light rise in the electrooculogram.