What is choroideremia?

Choroideremia, also known as choroidal sclerosis or progressive tapetochoroidal dystrophy (TCD), is a rare genetic condition that causes the loss of eyesight progressively from childhood due to the gradual loss of cells in and around the retina, which is the light-sensitive layer at the back of the eye.^1,2

What causes choroideremia?

This condition occurs due to damage to the choroid, which is the network of blood vessels that supply the retina with blood and vital nutrients such as oxygen, which is essential for the retina to remain healthy.^1,2 If there is damage to this network, the cells around the retina are damaged, leading to vision loss.^1,2

Damage to the choroid is caused by a genetic change called a mutation in the CHM gene, resulting in the degeneration of the choroid and, therefore, the retina.^1,2

How is choroideremia inherited?

The CHM gene is located on the X chromosome, which females have 2 copies of, while males have 1 X chromosome and 1 Y chromosome.¹ Generally, only one of the X chromosomes will carry a copy of the mutated CHM gene, so in affected females, the second X chromosome can compensate for this mutation; however, in males, as there is only one X chromosome, one faulty gene is enough to cause symptoms.^1,2

This is  called an X-linked recessive pattern, and it explains why people assigned male at birth are far more likely to develop choroideremia with more severe symptoms than those assigned female at birth.^1,2

What are the symptoms of choroideremia?

It is almost always found in males and is first seen in early childhood as night blindness, which is when it becomes difficult to see at night or in dark rooms.^1,2 This is followed by progressive loss of peripheral vision, leading to ‘tunnel vision and then onwards to the loss of central vision as the individual ages into late middle age and further.^1,2,3 Some individuals may even experience issues with colour vision and contrast vision, even if their central vision is still working. ^1,2 All of these symptoms can vary in severity and tend to be less severe in females if they are affected by choroideremia.

How is choroideremia diagnosed?

Choroideremia is first suspected if there has been a vision change or if an optician has observed possible signs during a routine eye examination.^1,2

An ophthalmologist (eye doctor) will then conduct specific tests to look for choroideremia, as well as look at the family history and do genetic testing to identify the mutated gene.^1,2

What are the treatments for choroideremia?

Currently, there is no approved treatment for choroideremia, but there are ways to manage this condition and make it easier for individuals to see better and improve their quality of life.^1,2,4

Low vision devices for choroideremia

Low vision devices (LVDs) are devices which help individuals use their sight to better advantage.⁴ These lenses are used to improve sight on two ideas: BBB and CCC.⁴ BBB is bigger, brighter, and blacker, and CCC is closer, colour, and contrast.⁴ The underlying principle of all LVDs is to improve basic vision.⁴

High plus reading glasses

Sometimes, regular glasses aren’t enough to help with reading, particularly with conditions such as choroideremia.⁴ In cases like this, special, strong, reading glasses called high plus lenses are used.⁴

Doctors usually start with lower prescription glasses and slowly increase the strength until standard-sized text can be read comfortably. These glasses work by making text and objects look bigger, and the stronger the lenses, the higher the magnification, i.e. the closer the reading material needs to be held.⁴

Types of glasses available:⁴

Full-field glasses - cover the whole lens area

Half-frame glasses - let you look over the top when not reading

Prism glasses - help both eyes work together when reading very close, reducing eye strain

Magnifiers

Magnifiers are tools that make text and objects look bigger and clearer. They can be used together with regular reading glasses.⁴ Compared to strong reading glasses, magnifiers let you hold things a little farther away, which some people find more comfortable.⁴ However, the farther the object is, the smaller the area you can see at once.⁴

There are many types of magnifiers:

Hand-held magnifiers - Small, portable, and affordable. They’re useful if you need to move your eyes slightly to see better (eccentric viewing). The main limitation is that they show only a small area at a time and must be held steady at the correct distance.⁴

Stand magnifiers - These rest on the page, so you don’t have to hold them up. They can come with built-in lights and different focus settings because they sit on a stand; they are easier to use for people with shaky hands, arthritis, or poor hand control.⁴

Dome magnifiers - Shaped like a clear paperweight, they are placed directly on the page.⁴ They gather light well, making text look brighter as well as bigger.⁴

Bar magnifiers - Shaped like a small bar, they are designed to magnify one line of text at a time, which helps with reading long paragraphs.⁴

Fresnel sheet magnifiers - Made from a very thin piece of lightweight plastic, these act like a lens with tiny ridges.⁴ They are inexpensive, easy to carry, and can be placed over a whole page.⁴

Telescopic contact lenses

Telescopic contact lenses are special lenses designed to make things look bigger and easier to see.⁴ When used together with strong glasses, they can provide up to 2x magnification and give a wider field of vision.⁴ Unlike bulky spectacle-mounted telescopes, these lenses look just like normal contacts, so they are more discreet and cosmetically acceptable.⁴

However, the magnification they provide is limited, which means they are most helpful for people with mild to moderate vision loss, rather than those with very poor vision.⁴

Non-optical systems

Non-optical systems can be helpful for individuals with low sight, using strategies such as large print books and better lighting/illumination. ⁴

Electronic devices

Video magnifiers

One of the most helpful electronic tools for individuals with low vision in conditions such as choroideremia is the video magnifier, also called a CCTV system.⁴ It works by capturing the text or object with a camera and displaying a larger, clearer version on a TV or computer screen.⁴ These devices solve common problems of regular magnifiers, such as needing to hold things very close, seeing only a tiny area, or struggling with poor contrast and lighting.⁴

Retinal protection strategies

UV-blocking sunglasses and filters

Long-term exposure to ultraviolet (UV) rays from the sun or tanning beds can contribute to further retinal damage, so it is important to wear sunglasses with adequate UV blockage to protect the eyes effectively.⁴ Using blue light screen protectors on mobile devices and computer screens can also help protect the retina and decrease the damage to it.¹

Diet

Avoiding smoking and eating a healthy diet of fresh fruit and green leafy vegetables can also help to limit retinal damage.^1,2

Summary

Choroideremia is a rare, inherited eye condition that mainly affects men and leads to gradual vision loss starting in childhood. It is caused by mutations in the CHM gene, which damage the blood vessels and support structures of the retina. The disease is usually passed down in an X-linked recessive pattern, which explains why women are often carriers with milder or no symptoms.

Although symptoms progress over time, typically beginning with night blindness and later narrowing of peripheral vision, early diagnosis through eye exams, family history, and genetic testing is important. Detecting choroideremia early allows patients and families to prepare, access supportive therapies, and consider participation in emerging research and clinical trials.

Though there is currently no cure for choroideremia, supportive therapies can make a real difference in daily life. Low vision aids such as strong reading glasses, magnifiers, telescopic contact lenses, video magnifiers, and simple adjustments like better lighting or large-print materials help people use their remaining vision more effectively. Protecting the retina through healthy lifestyle choices, such as wearing UV-blocking sunglasses, eating a diet rich in leafy greens and antioxidants, and avoiding smoking, may also help slow further damage.

By combining these approaches, individuals with choroideremia can maintain independence, improve comfort in everyday tasks, and enhance overall quality of life while researchers continue to work toward future treatments.