What is Retinitis Pigmentosa?
Retinitis pigmentosa (RP) is not one eye disorder, but rather a group of related eye disorders that cause progressive vision loss.1
What causes retinitis pigmentosa?
It’s an inherited disorder stemming from a mutation in any one of more than 60 genes and affects approximately 1 in 4000 people.1,2 The genes that cause RP hold instructions for making proteins necessary for retinal cells, called photoreceptors.2 Photoreceptors can either be rods or cones; rods enable vision in low light, and cones are involved in vision in bright light, as well as color vision. If there are any changes to the protein, various effects can occur: the cell may not be functional, toxic proteins may be made, or general damage to photoreceptors occurs. Mutations in any of these genes eventually lead to a loss of rods and cones in the retina, affecting vision.
How is retinitis pigmentosa diagnosed?
Only an eye care professional can diagnose RP, which includes a retinal examination. An ophthalmoscope will be used, which allows the doctor to see the retina. Upon examination, RP typically presents with abnormal, dark pigment streaks on the retina, hence the name of RP.2 Other tests that may be used include2:
- Electroretinogram (ERG): This test measures electrical activity of photoreceptor cells. A gold foil or special contact lens is placed on the eye with electrodes attached to it. A flash of light is transmitted to the retina, and the electrodes help measure the responses of the rods and cones. Individuals with RP have decreased electrical activity due to the impairment of photoreceptors.
- Visual field testing: This test is done to evaluate the extent of vision loss. A noninvasive test, patients typically have to follow a light that is moved around a space in front of and on the sides of the head.
- Genetic testing: this is not always done, but sometimes a doctor will take a DNA sample to see the specific type of RP that a person has. This may provide some information about how the disorder will progress.
What are the symptoms of retinitis pigmentosa?
The first symptom of RP typically occurs in childhood and is a loss of night vision.1 It might also become more difficult or take longer for eyes to adjust to changes in lighting.2 Sometimes children might develop photophobia, or have significant discomfort in bright lighting.2 The exact progression of RP can vary widely, due to different mutations on different genes, so each person’s experience of RP can be different as time goes on.
Retinitis pigmentosa progression
As time goes on, many people with RP develop blind spots in their peripheral vision, which eventually worsens and they experience tunnel vision.1 Still later, as the disease progresses further, central vision is eventually affected, and individuals with RP become legally blind.2
For most people, RP symptoms are limited to vision loss; when this occurs, the RP is called nonsyndromic. In some people, RP is part of different syndromes that affect other parts of the body and other tissues in the body, and this form of the disease is called syndromic. Usher syndrome is the most common syndromic form of RP; this involves vision loss and hearing loss that occurs early in life.1
How is retinitis pigmentosa treated?
Treatment for RP is done with a team of various caregivers, including an eye doctor, occupational therapist (OT), orientation and mobility specialists, certified low vision therapists, and other professionals. Living with impaired vision from RP involves a variety of challenges, but these can be met with multi-disciplinary treatment and care. In the early stages, low vision aids can be helpful, along with computer programs that read text, closed-circuit televisions, and lighting devices. Learning to use a cane or guide dog with a mobility specialist can help children maintain independence, and the treatment team can work with the school to ensure the appropriate accommodations are in place.
Vitamin A for retinitis pigmentosa
A clinical trial found that a daily dose of 15,000 IU of vitamin A palmitate slowed the progression of the disease in adults, but given the diversity of types of RP, this might not be effective for everyone. If you or your child has RP, talk with the doctor to see if taking vitamin A palmitate might be appropriate for treatment.
The Argus II is an artificial vision device that has been used for late-stage RP. It’s a prosthetic device consisting of a light-sensitive electrode that is surgically implanted on the retina.2 Glasses with an attached camera transmits signals to the electrode, which are then sent to the brain.2 It does not provide normal vision, but it does help those with RP navigate without mobility aids and helps them to read large print. While it has not been proven effective, the FDA has allowed it to be used through a humanitarian exemption, which means the benefits outweigh the risks.2 Medicare may cover this, so it may be worth discussing with the doctor to see if it’s an appropriate treatment option.
Retinitis pigmentosa research
More research is being done with gene therapy and other types of therapy, like drug and nutritional therapies, to help those with RP. Each person has different needs as RP progresses, and since the disease course can vary, talk with your doctor about any challenges and needs that arise, and what can be done to help address these issues.
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