Clinical findings in patients with congenital stationary night blindness of the Schubert-Bornschein type.

We examined 23 patients (18 families) with congenital stationary night blindness (CSNB) who showed a "negative" electroretinogram of the Schubert-Bornschein type. The goal of the study was to find evidence for the classification proposed by Miyake (complete and incomplete type) based on electroretinograms (ERGs) and dark-adaptation function and to look for additional classification parameters that argue for or against heterogeneity. In all, 13 patients revealed the complete type and 10 the incomplete type. The mean age of our patients was 24.7 years (median, 21 years; SD, 14.5 years). In both groups, almost all patients were myopic (mean, -6.05 D; SD, 3.77 D; median, -6.12 D), and there was a reduction in visual acuity (mean, 0.34; SD, 0.14; median, 0.35) without significant differences between the subgroups. In all, 56.5% of the patients suffered from nystagmus and 52.2% squinted. These results confirm the Miyake classification and suggest that only ERG and dark-adaptation data allow a discrimination between the two subtypes. The ongoing molecular analysis will show whether there are correlates on the molecular level.