Congenital stationary night blindness

Congenital stationary night blindness (CSNB) is an inherited condition present from birth affecting the retina's ability to function properly in low light conditions, causing difficulty seeing in dim light or darkness. Unlike many other inherited retinal conditions, it is 'stationary', meaning it generally does not progressively worsen over time, distinguishing it importantly from progressive conditions like retinitis pigmentosa. Vision in normal daylight conditions is often relatively unaffected, though some forms also involve some reduction in daytime visual acuity.

It is caused by inherited genetic mutations affecting specific proteins involved in how the retina's rod cells (responsible for vision in dim light) process and transmit visual signals. Several different genes have been identified as potential causes, with different inheritance patterns depending on the specific gene involved, including autosomal dominant, autosomal recessive, and X-linked patterns. Genetic testing can identify the specific gene involved, which can also help predict whether any additional visual features, beyond night blindness, might be present.

The key distinguishing feature is that CSNB is generally non-progressive, meaning night vision difficulty, once present, typically remains relatively stable throughout life rather than gradually worsening, as occurs in progressive conditions like retinitis pigmentosa. This distinction is reassuring and important, since it means the long-term visual outlook and appropriate counselling differ considerably between these conditions despite some overlapping initial symptoms. Specific tests, including a detailed electroretinogram, help confirm this important distinction.

The main symptom is difficulty seeing in low light or darkness, often noticed as difficulty with night driving or navigating dimly lit environments, present from an early age. Depending on the specific genetic subtype, some people also have mild reduction in daytime visual acuity, short-sightedness (myopia), or other associated visual features. The specific combination and severity of features vary depending on the underlying genetic cause.

There is no treatment that changes the underlying retinal function, since this is a structural/functional difference present from birth, but management focuses on practical adaptations for low-light situations (such as being extra cautious with night driving or seeking additional lighting), correcting any associated refractive error with glasses, and genetic counselling for affected families. Since the condition is generally stable rather than progressive, ongoing intensive monitoring is often less necessary than for progressive retinal conditions, though periodic review remains valuable. Discussing practical strategies for managing night vision difficulty with a low-vision specialist can be helpful for some people.

See an ophthalmologist if you or a family member have unexplained difficulty seeing in dim light or darkness, particularly present from childhood, for specialist assessment including specific retinal function testing to help confirm the diagnosis and distinguish it from progressive conditions. NHS ophthalmology referral can take several weeks; a private consultation is typically available within about 2 weeks for earlier assessment.