Retinitis Pigmentosa: What It Is and How It Is Treated
This article gives an overview of retinitis pigmentosa, including its symptoms, causes, and treatments.
Retinitis pigmentosa is a group of rare eye diseases. These inherited conditions cause gradual vision loss.
Problems with vision usually start in childhood. However, the onset, speed, and extent of vision loss can vary depending on the form of the disease. It usually does not lead to total blindness.
There are three different ways to inherit retinitis pigmentosa:
- Autosomal dominant: With this form, it only takes one copy of a gene to inherit the disease. Having a parent with the condition means a child has a 50% chance of inheriting both the gene and condition.
- Autosomal recessive: With this form, it takes two copies of the gene to inherit the disease. A parent can be a carrier, meaning they have the gene but not the disease. In this case, a child has a 50% chance of being a carrier, a 25% chance of inheriting the disease, and a 25% chance of neither being a carrier nor having the disease.
- X-linked: Only females carry the gene in this form. Because males have one X chromosome, they have a 50% chance of inheriting the disease. Females have two X chromosomes, so they have a 50% chance of being a carrier. The other X chromosome will prevent a female from having the disease.
Because of the different inheritance patterns, it is important to know which form you have. Genetic counseling and prenatal testing are available for parents who are carriers of genetic diseases.
Retinitis pigmentosa is an inherited eye disease, and there are more than 100 different genes that can cause it. Mutations in these genes cause problems with photoreceptor cells.
These cells in the retina absorb light and convert it into electrical signals, which the brain then processes into images.
There are two kinds of photoreceptors: rods and cones. Rods are on the outer edge of the retina. They process light in dim or dark conditions. The disease usually affects rods first. As rods stop working, low-light vision suffers.
Cones, which process color and detail, are more central in the retina. As the disease progresses to the cones, visual acuity, and visual field decrease.
Vision loss is the main symptom of retinitis pigmentosa. Vision problems are progressive and usually begin in childhood. The speed and extent of these issues will depend on the specific form and mutation.
In the early stages, the disease affects the rods. This leads to problems with night vision and seeing in dim lighting. As the disease progresses, other vision loss symptoms include:
- loss of side vision or peripheral vision, leading to tunnel vision
- problems with central vision, which can make reading and other detailed tasks difficult
- problems with color vision, as the cones degenerate
There is no cure for retinitis pigmentosa. Most people will lose most of their vision over time. However, total blindness is uncommon.
Diagnosing retinitis pigmentosa starts with an eye exam. This includes using an ophthalmoscope to view the retina. In retinitis pigmentosa, there will be dark deposits of pigment on the retina.
Other testing includes:
- Electroretinography: This test measures the electrical activity in the retina and tells doctors how well it reacts to light.
- Optical coherence tomography: This is an imaging exam that takes very detailed pictures of the retina.
- Visual field testing: This test can check your side vision and find blind spots.
Genetic testing can assist doctors in diagnosing retinitis pigmentosa. This testing can look for genes that cause the disease.
Knowing which gene you have is important. It gives your doctor information about the likely course and severity of your disease. It also lets your doctor know if gene therapy is an option for you.
There is no cure for retinitis pigmentosa. Because there are so many different versions of the disease, there is also no standard treatment.
In the past, people used vitamin A supplements to help slow the progression of the disease. There is some doubt about the effectiveness of this treatment. Additionally, too much vitamin A can be dangerous and can make other eye conditions worse. Currently, the American Academy of Ophthalmology recommends against using vitamin A to treat retinitis pigmentosa.
Low vision aids
The main way to treat retinitis pigmentosa is with low vision aids. There are several strategies to help with low vision.
A low vision specialist can help you find the right tools. Here are some examples:
- closed-circuit televisions and monitors
- mobility assistance with canes or guide dogs
- portable light devices
- special lenses that can reduce glare
- text readers
Some people develop retinal swelling, cataracts, and other conditions. There are medications and procedures that can treat these if they develop.
There are also retinal implants for people with advanced disease and very low visual acuity.
For people with a specific gene mutation, RPE65, there is a way to treat the disease. This treatment uses the gene therapy medication voretigene neparvovec-rzyl (Luxturna).
The therapy involves an injection under the retina to deliver a healthy copy of RPE65 to the affected area.
This gene therapy can help to make the retina responsive to light again. Many people who get this treatment are able to see objects and move around with awareness of those objects. Research continues for other gene mutations.
Retinitis pigmentosa is a group of rare, inherited eye diseases. It usually begins in childhood and gets progressively worse. Due to the different variations of this disease, the rate and extent of vision loss vary.
While there is no cure, gene therapy is available for people with the RPE65 mutation. Otherwise, treatment involves managing low vision, possibly with retinal implants.