Congenital stationary night blindness.

Congenital stationary night blindness (CSNB) seems to be a very rare condition in Scandinavia. From Denmark a 7-generation family with the dominant form was published in 1909, and one family with the X-linked recessive form was reported from Norway. On going through the files of the National Eye Clinic for Visually Impaired, 7 patients were found (1 dominant, 4 X-linked recessive, 1 simplex case and 1 autosomal recessive). Including anamnestic information on relatives, 17 patients had a diagnosis of CSNB. The clinical findings in these cases are reported with stress on alteration in ERG, dark adaptation and the optic discs. The loss of oscillatory potentials in a carrier of CSNB is described. The provisional findings seem to indicate that 3 genetic variants are present in the Danish population. The real prevalence is estimated considerably higher than 17 out of 5 million.