Note: This article is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.
- Retinitis pigmentosa (RP) is a group of eye diseases that affect the retina. The retina, which is located at the back of the eye, sends visual images to the brain where they are perceived. The cells in the retina that receive the visual images are called photoreceptors. There are two types of photoreceptors: rods (which are responsible for vision in low light) and cones (which are responsible for color vision and detail in high light).
- In RP, the photoreceptors progressively lose function. Side vision, called peripheral vision, slowly worsens over time. Night vision is also affected. Central vision typically declines in the advanced stages of the disease.
- Most cases of retinitis pigmentosa are inherited. However, some people develop the disease even if they have no family history. Others may develop the condition as part of another disorder, such as Kornzweig disease, Kearn-Sayre syndrome, Waardenburg syndrome, Alport syndrome, or Refsum disease.
- Signs of RP can usually be detected during a routine eye exam when the patient is around 10 years old. However, symptoms usually do not develop until adolescence.
- Worldwide, RP is thought to affect roughly one out of 5,000 people.
- Although the disease worsens over time, most patients retain at least partial vision, and complete blindness is rare. There is currently no known cure or effective treatment for retinitis pigmentosa, but there are some possible ways to manage the condition.
Signs and Symptoms
- Symptoms of retinitis pigmentosa (RP) vary among patients. The speed at which the disease progresses also varies.
- The first sign of the disease is typically poor night vision or difficulty seeing in dim light. This is generally followed by limited side vision (peripheral vision) and difficulty seeing detailed images. Over time, the disorder may cause tunnel vision, which occurs when the outer edges of vision are dark, so that only objects directly in front of the eye can be seen.
- When patients are exposed to bright light or sunlight, they often experience a glare that makes it difficult to see.
- Central vision usually starts to deteriorate in the later stages of the disease. Symptoms of central vision loss include difficulty reading or seeing detailed images.
- Some people with RP may eventually go blind, although most people are able to maintain some vision throughout their lives.
- Eye examination: An ophthalmologist (eye doctor) can diagnose retinitis pigmentosa (RP). Usually, the doctor uses a special instrument, called an ophthalmoscope, to view the inside of the eye, where the retina is located. If the patient is healthy, the doctor will see an area called the fundus that is orange to red in color. However, if the patient has RP, the fundus will have brown or black spots.
- If RP is suspected, an ophthalmologist may confirm a diagnosis by performing an electroretinogram (ERG). This test measures the function of the retina. During the test, different-colored lights are flashed into the eyes as the patient looks at a large reflective globe. An electrode is placed on the eye, and a wire transmits a record of the eye’s retinal activity. People with RP have reduced electrical activity in the retina, which indicates that the photoreceptors are not functioning properly.
- Visual tests can also be performed to determine the severity of vision loss.
- Genetic testing: Many different genetic mutations are known to cause retinitis pigmentosa. Currently, genetic testing is available for several genetic mutations, including RLBP1, RP1, RHO, RDS, PRPF8, PRPF3, CRB1, ABCA4, and RPE65.
- Blindness: Retinitis pigmentosa (RP) causes vision loss that worsens over time. Some people may eventually become blind, although this is rare.
- Cataracts: Patients with RP often develop a type of cataract called subcapsular cataracts. When this occurs, the lens becomes cloudy and vision is impaired. Eyeglasses may improve symptoms when cataracts first develop. Later on, surgery may be needed to restore vision.
- Retinal detachment: Some patients may experience retinal detachment, which occurs when the retina separates from its attachments to the back of the eyeball. Without prompt treatment, retinal detachment may lead to permanent vision loss.
- Interference with daily activities: RP may eventually interfere with daily activities. It may become difficult to drive, especially at night. Individuals are required to pass an eye test before obtaining a new license or renewing an existing license. Some people who have poor night vision may require restrictive driver’s licenses that only permit them to drive during the day.
General: Currently, there is no known effective treatment for retinitis pigmentosa (RP). However, there are some possible ways to manage the condition.
- Special glasses: Many patients experience glare when they are exposed to bright lights. A light amber filter can be added to general eyeglasses to help improve tolerance of bright lights.
- Vitamin A: Some research suggests that high doses of vitamin A (about 15,000 international units) may help slow the progression of the disease in some people. However, more research is needed to determine if this is effective. The normal recommended amount for adults is 900 micrograms for men and 700 micrograms for women. Based on recent findings, vitamin A in the palmitate form has been recommended in patients with RP.
- Vitamin A toxicity can occur if taken at high dosages. Excessive doses may cause nausea, vomiting, headache, blurred vision, dizziness, liver problems, and clumsiness. It may also increase a person’s risk of developing osteoporosis. Vitamin A appears safe in pregnant women if taken at recommended doses. However, excessive doses have been reported to increase the risks of some birth defects. Therefore, Vitamin A supplementation above the recommended dietary allowance (RDA) is not recommended during pregnancy. Use cautiously if breastfeeding because the benefits or dangers to nursing infants are not clearly established. Avoid if allergic to vitamin A. Use cautiously with liver disease or alcoholism. Smokers who consume alcohol and beta-carotene may be at an increased risk for lung cancer or heart disease.
- DHA: DHA is an omega-3 polyunsaturated fatty acid and an antioxidant. Some studies suggest that DHA may help treat RP, while others do not support this therapy. More research is needed to determine if DHA is a safe and effective treatment for this condition.
- Calcium channel blockers: Heart medications called calcium channel blockers, such as diltiazem (Cardizem®), have been suggested as a possible treatment for RP. According to some animal studies, calcium channel blockers may reduce the degeneration of the retina. However, not all studies have shown positive effects. Therefore, calcium channel blockers cannot be recommended until more research is performed.
- Gene therapy: Gene therapy is currently being studied as a possible treatment for RP. This type of experimental therapy involves replacing or deactivating mutated genes that are causing disorders. Other gene therapy techniques involve inserting a new gene to help the body fight a specific disease. A drug called ciliary neurotrophic factor (CNTF) has been shown to slow the degeneration of photoreceptor cells, although exactly how it works remains unknown. Early research shows that CNTF gene therapy may help stabilize (but not necessarily restore) vision in mice with RP. Gene therapy is experimental and is currently only available in clinical trials.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration .
A story of Struggle : Retinitis Pigmentosa Patient
A Family Affair
Bill Carty was 28, married and had three young children when he went out to play racquetball one day. It had been years since he’d last played, “and I was surprised that, when the ball hit the wall, it would vanish from my vision,” Bill, now 55, recalls. “But I knew, right away, what it meant.”
Bill Carty It meant that he probably had retinitis pigmentosa, or RP, a sight-stealing disease that begins with the loss of peripheral vision and progressively worsens. Bill guessed as much because, on his mother’s side, five generations of the family had been affected by it. So when he received the official diagnosis, he wasn’t so much surprised as disappointed. “Even though my mother had it, my father had always told me that I wouldn’t get it – just because he didn’t want me to get it,” Bill explains.
Like so many first diagnosed, Bill went through denial, which made sense. He had a family; he was just kicking off a career with aerospace and defense-technology giant Northrop Grumman. Going blind? he thought. I don’t have time for that. “But then I started walking into things,” he says. “I’d crash into other people’s carts in the grocery store. I knew I couldn’t ignore it anymore.”
Luckily, Bill had a couple things going for him. He was referred to ophthalmologist Dr. Samuel Jacobson, a Foundation-funded researcher whose work included studying family histories to identify the genes responsible for retinal diseases. It would take a few years, but Bill’s family gene was identified. This means that they’ll quickly learn of future treatments targeting that gene.
But Bill also had ties to the Foundation itself. His parents had volunteered and contributed to what was then known as the RP Foundation, and during a Foundation conference in Orlando, Florida, in the early 1990s, he discovered the tools he’d need to function at high levels, both personally and professionally.
“I was determined to be independent, but when I got to Orlando, it was intimidating, navigating that big crowd in the lobby,” Bill says. “But then I saw lots of people with canes and guide dogs, and they were doing a lot better than I was.” So he ordered a cane from a vendor and looked into getting a guide dog. After receiving mobility training, Bill “outed” himself, in essence – both at work, where he’s now vice president and general manager of the Defense and Government Services Division, and among friends and family.
At age 35, Bill also had to stop driving. Five years later, he took the next step and got a guide dog, which meant more training. Bill, now divorced from his first wife, recalls, “It turned out that the trainer of my dog and I became friends and, ultimately, more than friends. We got married. That’s Colleen.” Today, Colleen and Bill have a 12-year-old son.
Bill’s family history being what it is, he and his three sisters, who also have RP, have been active in Foundation chapters up and down the East Coast for the past 15 years, helping to raise, in his estimation, more than $3 million thus far. Bill, as a Foundation national trustee, is fully aware of the research it funds and has facilitated, especially recent gene therapies that show promise for the future treatment of RP.
“That’s extremely exciting,” Bill says. “And whether it makes a difference for my vision or not is irrelevant. When I speak to groups, I hold up five fingers. I’m the fifth generation in my family that we can count thus far that’s had RP. If we can stop it for the sixth and seventh generations, which are alive now, that’s what the Foundation is all about. And we will.”
story from : Foundation fighting Blindness