Retinitis pigmentosa (RP) is a group of very rare eye diseases that is hereditary and can lead to vision loss. But is there a cure? Here we take a look at this disorder.
What is Retinitis Pigmentosa?
This group of eye diseases involves changes to your retina, the layer of light-sensitive cells at the rear of your eyeball. The retina plays a big role in how we see: It’s responsible for passing nerve impulses to the optic nerve, which then sends those to the brain for interpretation.
With retinitis pigmentosa, certain cells (called rods and cones) don’t operate as they should, causing slow vision loss over time. These rods and cones break down or degrade and eventually die, making it impossible for them to absorb light and convert it to nerve impulses.
What are the causes of RP?
RP impacts about 1 in 4,000 people in the United States and around the world. It’s caused by mutations in any one of more than 50 genes. In some cases of RP, these mutations mean that the cells can’t produce the proteins necessary for the rods and cones to function. Sometimes the mutation causes the production of a protein that is toxic to the cell or that is abnormal.
Whatever the mutation, the result is that the rods and cones are irreparably damaged.
What are the symptoms of RP?
Symptoms usually show up in childhood, and one common symptom in children with RP is that they can’t see in the dark. That’s because the rods — which are responsible for helping us to see in dim light — are usually affected first. This causes people with RP to experience loss of both night vision and the side of their visual field, or their peripheral vision. Some may also develop tunnel vision.
Someone might experience this when they trip over things or have trouble with bright light.
Next, the cones die, which leads to a greater loss of the field of vision. Because the cones are responsible for helping us see color as well as detail, RP can also limit visual acuity and color vision.
Progression is different for everyone with this group of diseases. While some adults keep their central vision well into their 50s, others suffer from more severe vision loss decades earlier.
How is RP diagnosed?
An eye doctor will examine the retina to look for streaks of dark pigment deposits. These deposits are characteristic of RP, and are the reason for the name retinitis pigmentosa.
Your doctor may also do one or more of these tests:
- Electroretinogram (ERG): This measures the electrical activity of the rods and cones by sending a flash of light to the retina, then measuring cells’ responses using electrodes. If the ERG detects decreased electrical activity, this is indicative of a decline in the rods and cones functionality.
- Visual field testing: A visual field test involves watching a dot of light as it moves around a half-circle. The patient will then push a button when they can see the light, and the result is a map of the visual field.
- Genetic testing: A DNA sample from a patient can be used in certain cases to determine whether or not RP is present and how it might progress.
But is there a cure?
There is not a cure for RP, but there are services, devices and therapies that can help people with RP live with low vision and remain as independent as possible. Doctors are also continually working to discover and develop new treatments, including gene therapy, stem cell therapy, and replacement of damaged cells.
People with RP can benefit from working with a team of experts in addition to their eye doctor, including a vision specialist, occupational therapist, a mobility specialist, and others. This team can help someone with RP find the right combination of treatments and other therapies. Some of these include using special lenses that magnify central vision and eliminate glare, portable lighting devices, and computer programs that read text.
Skills can also be learned, including eye scanning techniques that optimize existing vision and learning to use a cane or a guide dog.
Here are some of the current treatments and options for living with RP:
- Medication: In some people, the tiny area at the center of the retina swells up, which further inhibits vision. A medication called acetazolamide can be prescribed to reduce swelling and improve vision.
- Vitamin A palmitate: In high doses, a clinical study showed that this can slow RP. However, too much of this compound is toxic, so those using this treatment should be sure to follow their doctor’s recommendations.
- Artificial vision device: Some people receive partially restored vision using an implant equipped with a camera and paired with glasses.
Even though there is no cure for retinitis pigmentosa, there is much that can be done to help people with RP thrive with low or declining vision. If you are struggling with vision problems, come and see us for an eye exam.