What is Choroideremia?
Choroideremia, also called progressive choroidal atrophy or choroidal sclerosis, is a rare genetic eye disorder that occurs due to a defect in the X-chromosome. It typically affects men. Choroideremia causes vision problems such as difficulty seeing at night, tunnel vision or gradual narrowing of the field of vision, and reduced ability to see things clearly and sharply. Choroideremia tends to remain undetected as it has symptoms similar to other eye disorders. However, it may lead to blindness so it is important to get a timely diagnosis and suitable treatment.
What are the Causes of Choroideremia?
Choroideremia occurs due to a genetic defect in the X- chromosome. As a result, a person develops problems with the gene that is related to Rab escort protein (REP-I) which controls retinal function. It is usually inherited by males, while females remain asymptomatic carriers.
What are the Symptoms of Choroideremia?
Choroideremia is characterized by a progressive deterioration of the outer retina, the retinal pigment epithelium (RPE) that consists of pigments that provide nourishment to retina cells, and the inner choroid (the layer supplied with blood vessels).
The common symptoms of choroideremia may include:
- Night blindness or impaired night vision also called nyctalopia
- Tunnel vision: gradual narrowing of the field of vision, also called peripheral vision loss
- Reduced visual acuity: loss of ability to see things clearly and sharply
- As the damage to the retina continues, it may lead to blindness
How is Choroideremia Diagnosed?
Your eye specialist/ophthalmologist will perform a comprehensive eye exam, check your medical history, and perform diagnostic tests such as:
Optical Coherence Tomography:
In this test, light waves are focused on the eye to generate images of the eye’s internal structures. This helps understand the underlying problem.
Fluorescein Angiography:
In this procedure, a fluorescent dye is injected into the vein in your arm. The dye travels through the bloodstream, reaches the eye, and highlights the blood vessels in the back of your eye. During this time, the eye is photographed. The images of the eye aid in proper assessment.
Electroretinography:
In this procedure, your doctor administers eye drops to numb the eye. Then a special contact lens-electrode is placed on the eye. You will watch a set of flashing lights to stimulate the retina. Then, the electrical signals generated by the rod and cone cells are measured by your doctor. An absent or weak signal of either the rod or the cone cells indicate a problem with the retina.
What are the Treatments Available for Choroideremia?
Choroideremia does not have a specific cure, however, there are treatment options available. Your doctor may prescribe you medications or glasses to manage your symptoms. However, with the advancements in science, the newer therapies that have been used to treat choroideremia include:
Gene Therapy:
In this treatment, a trained specialist inserts a gene into the targeted cell or cells to modify the protein that is responsible for the retinal malfunction.
Stem Cell Therapy:
In this treatment, special body cells called stem cells are used to treat retinal dystrophy (degeneration of the cells in the retina). The stem cells have the capacity to develop new tissues and repair damaged or diseased tissues and organs.
Retinal Prosthesis System:
In this treatment, an implantable electronic eye device called retinal prosthesis is placed in your eye. This retinal prosthesis system has the ability to stimulate the sensation of vision in the eyes of individuals with significant retinal diseases which includes choroideremia.
