Congenital stationary night blindness is a rare, inherited eye condition that primarily affects people assigned male at birth. It is not progressive, but there is no known treatment or cure.

Congenital stationary night blindness (CSNB) is the term for a group of rare genetic conditions that affect your ability to see in low light or darkness. If you or a loved one has this condition, you have had difficulty seeing at night since birth.

Doctors refer to it as stationary because the condition does not worsen. Your night vision stays about the same throughout your life.

This condition is typically inherited, meaning families pass it to the next generation.

In this article, we explore the causes of CSNB, who gets it, and how it’s inherited. We also discuss diagnosis, treatment, and outlook.

Changes or mutations in certain genes cause CSNB. These genes play a crucial role in how your eyes respond to light. When these genes don’t function properly, you may have difficulties seeing in low light or darkness.

Research has linked several specific genes to CSNB. For example, mutations in the GNAT, TRPM1, and LRIT3 genes have associations with different forms of this condition.

CSNB is a genetic condition, meaning it’s passed within families. The genes responsible for CSNB are usually inherited in one of three ways:

  • X-linked inheritance
  • autosomal recessive inheritance
  • autosomal dominant inheritance

In X-linked inheritance, the gene causing CSNB is on the X chromosome. People assigned male at birth typically have only one X chromosome and are more likely to show symptoms if they inherit a faulty gene. People assigned female at birth are usually born with two X chromosomes and can be carriers of the condition without showing symptoms.

Autosomal recessive inheritance means you must inherit two copies of the faulty gene — one from each parent — to develop CSNB. In these cases, parents may not show any symptoms but carry one copy of the faulty gene with the chance of passing it on to their children.

On the other hand, autosomal dominant inheritance means you only need to inherit the mutated gene from one parent.

CSNB can affect anyone, but it’s most commonly diagnosed in people assigned male at birth by age 28. This is primarily due to the way you inherit CSNB.

While the condition is present at birth, the symptoms, such as difficulty seeing at night, may not become noticeable until early childhood.

How rare is congenital stationary night blindness?

CSNB is a rare condition, and its prevalence worldwide is unknown. A 2019 study reported that 1 in more than 6,000 people get CSNB from the TRPM1 gene mutation. But there’s not enough data across all gene mutations for an accurate risk assessment.

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Diagnosing CSNB typically involves a series of tests, including an electroretinogram (ERG). This test measures the electrical responses of various cell types in the retina, including the light-sensitive cells called rods and cones. In people with CSNB, the ERG results often show specific irregularities that can help confirm the diagnosis.

Another important diagnostic tool is genetic testing. Since CSNB is a genetic condition, identifying the specific gene mutation can provide a definitive diagnosis. It also helps you understand how it’s inherited and can be useful for family planning.

Currently, there is no definitive cure for CSNB. However, advances in gene therapy offer promising potential treatments.

A 2021 study shows that substantial restoration of night vision is possible in adult mice with CSNB through gene therapy. Similarly, targeting nerve cells in the retina with a specific type of gene therapy has proven safe and effective in reversing some forms of CSNB.

Researchers also think photoreceptor (rods and cones) replacement by transplantation and gene therapy may help provide long-term relief for people with CSNB.

While these findings are promising, it is essential to note that they are still in the experimental stage. Animal studies do not necessarily reflect the effects or side effects on humans.

If you or a loved one has CSNB, discuss potential treatment options with a doctor. They may also guide you in protecting yourself from injuries that you could have due to reduced vision at night.

The outlook for people with CSNB generally remains stable over time.

While there is currently no cure for CSNB, advances in gene therapy are promising. Managing this condition often involves adaptations to improve night vision and overall quality of life.

Congenital stationary night blindness vs. retinitis pigmentosa

CSNB and retinitis pigmentosa (RP) are both genetic eye disorders, but they differ significantly in how they affect your vision. CSNB is stationary, meaning it does not progress over time. It primarily affects night vision and can be present from birth.

RP is a progressive disorder that worsens over time. It initially affects peripheral and night vision but can lead to complete blindness. Unlike CSNB, symptoms of RP often begin in early adulthood.

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CSNB is a rare genetic eye condition for which night blindness is a core symptom. It does not get worse with time. However, there is no cure or treatment for it other than adapting so you can have a comfortable life.