An abnormal sub-type of congenital stationary night blindness (CSNB), a heterogeneous class of rare genetic conditions affecting bipolar cells, photoreceptor cells, and the retinal pigment epithelium (RPE). CSNB Type 1 subtype A exhibits abnormal photoreceptor inner segments even with a normal fundus examination. It also shows normal a- and b- waves of an electroretinogram.
