Various conditions causing poor night vision, sometimes called night blindness, have been known for centuries. Many disorders of the retina cause night blindness and most of these are progressive and associated with other ocular disease. However, several conditions causing difficulties with night vision are not progressive nor are they part of other syndromes. These are generally referred to as congenital stationary night blindness (CSNB).
Difficulty seeing at night is the primary symptom of congenital stationary night blindness. The condition is present at birth and does not progress. Daytime vision may be reduced to some degree as well. Mild color vision defects can sometimes be detected.
In this disease (CSNB1C) the daytime vision is rarely normal and may be severely reduced. However, night vision is seriously impaired. A few patients have ‘dancing eyes’ (nystagmus) and crossed eyes. Both sexes are affected and some patients are nearsighted.
At least 8 different mutated genes are known to cause CSNB. This type (CSNB1C) is inherited in an autosomal recessive pattern which requires that both parents contribute the specific mutation.
Diagnosis is based on an ophthalmological examination. An electroretinogram (ERG) test is important to establish the diagnosis and to rule out other retinal disease. This is a stationary disease without significant progression and no systemic disease is present. Lifespan is normal. Low vision aids are helpful in many cases.