All about Choroideremia: a rare disease that causes gradual loss of vision

Do you also feel like your vision is getting worse at night? Or is your peripheral vision, that is, your vision to the sides, gradually getting worse? Sometimes we don't pay much attention to these things, but they can be a sign of a serious underlying condition. Today we are going to talk about a rare, but very important to know, disease that can gradually lose vision and even lead to blindness. This is called choroideremia.

What is this choroideremia?

Simply put, Choroideremia is a rare, hereditary eye disease that is passed down through genes. It causes vision in both eyes to gradually deteriorate, eventually leading to blindness. This disease often affects men more severely.

You may have heard of another eye disease called `(Retinitis Pigmentosa).` It also causes the retina to gradually weaken. Surprisingly, the symptoms and some test results of both diseases, `(Choroideremia)` and `(Retinitis Pigmentosa), can be similar. Therefore, the best way to know exactly which of these two diseases you have is to get a `(genetic test).`

What happens inside the eye? How does this affect vision?

Our eyes are like amazing cameras. Inside the eye, there is a part called the retina . This is where special cells called photoreceptor cells are located that can detect light. These cells take the light that enters the eye and convert it into electrical signals. These signals are then sent to the brain along the optic nerve . The brain uses these signals to create the images we see.

Now, behind this retina, between the white protective outer covering of the eye (sclera) and the retina, there is a layer called the choroid . This choroid is where the retina gets its nourishment, that is, it has blood vessels that supply it with blood. Think of it like giving water and nourishment to a plant.

In choroideremia, the blood vessels in the choroid become damaged. Then, the retina does not receive enough blood, so it also begins to be damaged. This especially affects our peripheral vision .

How common is Choroideremia?

This is a very rare disease. Roughly speaking, it is estimated that only one in 100,000 or one in 50,000 people develop this disease . This means that even in our country, there may be a very small number of people with this disease.

What are the symptoms of this disease? See if you have these too.

The symptoms of choroideremia do not appear suddenly. They develop gradually. Here are some of the main symptoms:

• Night blindness (night blindness) is one of the first symptoms. Sometimes this symptom can appear in children under the age of 10. Imagine, even in a dimly lit place where others can see well, these people cannot see well.
• Weak peripheral vision. This means that when you look straight ahead, you can't see things to the sides. It can feel like you're looking through a tunnel.
• Decreased visual acuity. The ability to see things clearly and sharply decreases. It may be difficult to read letters and distinguish distant objects.
• Inability to recognize colors properly. The way colors appear may change. Some colors may even be difficult to recognize.
• Gradually, the side vision is completely lost, leading to blindness. At first, the side vision is reduced, over time only the central vision remains, and finally, complete vision may be lost.

Important: If you have one or more of these symptoms, do not assume that it is choroideremia. However, it is very important to see an ophthalmologist immediately for an examination.

Why does Choroideremia occur? Is it hereditary?

Yes, as we said before, Choroideremia is a genetic disease. To be precise, it is an X-linked genetic disorder.

We all have things called chromosomes inside our cells. These chromosomes contain our genes. Females have two X chromosomes (XX). Males have one X chromosome and one Y chromosome (XY).

The defective gene that causes choroideremia is located on the X chromosome.

Now, even if a woman has one X chromosome with this defective gene, if the other X chromosome is healthy, it will probably not have much of an effect. Therefore, women with this defective gene (`carriers`) usually do not suffer as severely from choroideremia as men. However, they can also develop symptoms such as night blindness as they age. However, complete blindness is very rare.

However, males only have one X chromosome. So, if they have this defective gene on that X chromosome, they are more likely to develop choroideremia.

A male with this disease passes his defective X chromosome to his daughters . Those daughters then become carriers of the disease. Those carrier daughters have a 50% (one in two) chance of passing on the defective X chromosome to their children.

How is Choroideremia diagnosed? What tests are done?

If you have any of the symptoms mentioned above, you should definitely see an ophthalmologist. He or she will examine your eyes thoroughly. In addition to a regular eye exam, you may be asked to do some special tests, such as:

• Electroretinogram (ERG): This test measures how your retina responds to light. Although it may seem like a complicated test, it's actually not very painful. Small electrodes are placed on your face, around your eyes, and on your scalp. Then, a very thin wire (maybe a lens) is placed directly into your eye, just above your lower eyelid. The room is then darkened and different lights are shone into your eyes to see how the cells in your retina are working. This can provide valuable information about how your retina is working.
• Optical Coherence Tomography (OCT): This is also a painless, non-invasive test. It is like a scan of the inside of your eye. It uses special light beams to take cross-sectional images of the inside of your eye, especially the retina and choroid. This can clearly show the thickness of these layers and any damage they may have caused.
• Fluorescein Angiography: In this test, a special dye is injected into a vein in your arm. As the dye travels through the blood vessels in your eye, a special camera takes pictures of the inside of your eye. This can help to see the condition of the blood vessels in the choroid and retina, such as whether they are damaged or bleeding.
• Genetic testing: This is the most reliable way to differentiate between Choroideremia and other diseases with similar symptoms, such as Retinitis Pigmentosa. This involves taking a sample of your blood, hair, skin, tissue, or sometimes amniotic fluid from your baby in the womb, and testing the genes in it. This can help determine if you have a mutation in the gene that causes Choroideremia.

Is there a treatment for Choroideremia?

Unfortunately, there is no cure for choroideremia. This may make you feel sad, but that's normal.

However, that doesn't mean we can't do anything. Even though the disease cannot be cured, we can treat other problems caused by the disease. For example:

• Low vision strategies: As vision gradually decreases, there are various devices that can help with everyday tasks. Examples include magnifying glasses, special lighting devices, and talking watches.
• Counseling for mental health: Living with an incurable illness like this can be mentally challenging. Therefore, it is very important to seek help from a psychiatrist or counselor.
• Genetic counseling: Since this is a genetic disease, genetic counseling is very useful to make other family members aware of this and to understand how it may affect future generations.

What kind of future does someone with Choroideremia have?

Typically, a person with choroideremia will lose their peripheral vision over time. Eventually, only central vision may remain. After that, some people may become completely blind. This can vary from person to person. Some people lose their vision over time, while others lose it over time.

Don't be discouraged by this. Medical science is advancing day by day. New research and new treatments are constantly being sought.

How do I take care of myself?

Even if you have been diagnosed with choroideremia, there are things you can do to take good care of yourself. Maintaining a healthy lifestyle is very important, even with this condition.

• Eat a good nutritious diet. Eat more green vegetables, fruits, and lean meats. Reduce excess salt, sugar, and unhealthy fats as much as possible.
• Get enough exercise. Even something as simple as a daily walk is good.
• If you smoke, stop. Smoking is not only bad for your eyes, but also for your entire body.
• See your eye doctor regularly to get your eyes checked. That way, you can learn about the status of your condition and new treatments.
• Get enough sleep.

When should I see a doctor?

If you notice any changes in your vision, such as decreased night vision, decreased peripheral vision, or blurred vision, see a doctor immediately. Especially if you experience sudden changes in vision or eye pain, this may be a medical emergency.

Also, if you're finding it difficult to do your daily activities, talk to your doctor about that too. It may be a good idea to ask if you're eligible to participate in things like gene therapy trials .

What is the difference between Choroideremia and Gyrate Atrophy of the Choroid and Retina?

Both of these diseases are genetic conditions. The symptoms may be similar. However, there are clear differences between the two.

• Inheritance pattern: Choroideremia is an X-linked disease. This means that it is inherited through the X chromosome. Gyrate Atrophy of the Choroid and Retina is an autosomal recessive disease. This means that in order to develop the disease, a child must inherit the defective gene from both the mother and father.
• Mutated gene: The gene mutation that causes both diseases is also different.

The most important things we need to learn from this (Take-Home Message)

It is true that choroideremia is a rare, incurable disease that can gradually lead to vision loss and even blindness. It is normal to have mixed feelings when you learn that you have such a disease.

But remember, you are not alone. Maintain a strong relationship with your medical team. They are there to support you. Research is ongoing to find treatments and cures for choroideremia, as well as other genetic diseases. And, there are already resources and services that can help with your needs. Accepting the help of others can make your life a little easier.

Always have hope. With the advancement of medical science, new treatments may emerge in the future.

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