Choroideremia - What Is It?

Choroideremia is a serious eye condition that can significantly affect a person's sight. It's characterised by a progressive loss of sight and it has many similarities with retinitis pigmentosa. What causes choroideremia and how can it affect you? Find out in this article.


What is Choroideremia?

It's a rare hereditary eye condition, affecting 1 out of 50,000 to 100,000 people. It affects mainly men and, while women can also be carriers, it usually doesn't have a significant impact on their health.

Choroideremia affects diverse eye parts involved in the transmission of the light into the eye and makes them deteriorate over time. These are the choroid, the photoreceptors and the retinal pigment epithelium. It is a progressive condition, but the rate at which it develops varies from person to person. It can eventually lead to blindness.

Since it closely resembles retinitis pigmentosa in its early stages, choroideremia is often difficult to detect and often misdiagnosed. As it is a hereditary condition, genetic testing is usually required to make an effective diagnosis.


What are the symptoms of Choroideremia? 

There are a number of symptoms that can indicate you have choroideremia, so proper diagnosis by a specialist is always advised. Those symptoms include:

  • Night blindness or difficulty to see in the dark; this is usually the first symptom to appear and can normally be experienced in childhood.
  • Loss of peripheral vision that can develop into tunnel vision.
  • Loss of central vision in more advanced stages of the condition.  

This condition inevitably leads to blindness as it progresses through the life of the patient. This normally occurs in late adulthood, but the speed at which it occurs can vary. 


What causes choroideremia?

Choroideremia is caused by mutations in the CHM gene. It is inherited in an X-linked recessive pattern. This means that:

A man with a mutated gene will have the condition and pass this gene to his daughters, but not to his sons. His daughters will become carriers of the condition, but won't develop it unless they also inherit a mutated gene from their mother. Even in these cases, women are usually not significantly affected by the condition.

Men only need one to have one mutated copy of the gene to develop the condition, so this will depend on whether they inherit a mutated X chromosome or a healthy X chromosome from their mother. This is why choroideremia appears more frequently in men. 

Is there treatment for choroideremia?

While there is no cure for choroideremia, gene therapy has been recently showing positive results when it comes to stopping the progress of the condition. The effectiveness of other therapies is also being tested and there is optimism that a cure might be found.

In the meantime, there are different tools that can help you make it easier to live with choroideremia:

  • Magnifiers: This condition causes a progressive and significant vision loss, which is why the use of magnifiers can be very handy in order to perform daily tasks with as little effort as possible. Even in the more advanced stages of the condition, there are plenty of powerful magnifiers that can help you make the most of your remaining sight, such as video magnifiers.
  • Sunglasses: Excessive sun exposure can accelerate the progression of this condition, so protecting your eyes from the sun by using high quality sunglasses with 100% UV protection can also help.

If you smoke, quitting is also recommended, as it's usually been identified as a major risk factor for diverse eye conditions.

Adapting to this lifestyle can be challenging, and counselling might be helpful. If one of your loved ones is affected by choroideremia, supporting them and being there for them as they adapt might be the best way to help them.