Congenital stationary night blindness (CSNB) refers to a group of nonprogressive retinal disorders characterized predominantly by abnormal function of the rod system. The condition may be X-linked (the most common form), autosomal recessive, or autosomal dominant.
CSNB, especially the autosomal recessive and X-linked forms, can present in early infancy with nystagmus and normal fundi. These forms are often also associated with myopia and decreased acuity in the range of 20/200. However, the range of vision in these patients is wide and, occasionally, patients have normal vision. The retina usually appears normal, although the optic nerve may show myopic tilt and temporal pallor. An ERG must be performed for diagnosis. The most common ERG pattern seen in CSNB is the “negative” dark-adapted ERG: a large a-wave and a reduced (negative) b-wave. Dark adaptation is abnormal in all patients with CSNB. Infants with CSNB may have a flat ERG until approximately 6 months of age, when it converts to the classic negative configuration.
Oguchi disease and fundus albipunctatus are forms of CSNB with abnormal fundi. In Oguchi disease, the fundus displays a yellow sheen after exposure to light; this sheen disappears following dark adaptation. In fundus albipunctatus, the retina develops yellow-white dots.
CSNB is also discussed in BCSC Section 12, Retina and Vitreous.