What is Retinitis Pigmentosa (RP)?
Retinitis Pigmentosa, also known as RP, is an inherited, genetic, eye disease, that causes retinal degeneration. This disease affects one in every four thousand people. RP causes the retina, which is the light-sensing cells in the back of the eye, to deteriorate. The result of this degeneration is the loss of peripheral vision, loss of central vision, night blindness, and sometimes blindness.
Currently, it is estimated that about one in every 4,000 people worldwide suffers from retinitis pigmentosa. Although it is not common, Dr. Larry M. Chism, Low Vision Specialist in Texas, is helping patients from all over Texas, including Abilene, treat this condition to maximize one’s remaining vision.
There are various forms of RP including, Usher syndrome, Leber congenital amaurosis, and Bardet-Biedl syndrome.
Relationship Between Photoreceptors and Retinitis Pigmentosa
Photoreceptors are located in the retina and are the first step in the process of sight. They absorb and transform the light that you see into electrical signals. These signals are then sent to other retinal cells, to the optic nerve, and ultimately to the brain. Your brain processes them into the images that make up vision.
There are two types of photoreceptors: rods and cones. Rods are in the outer portions of retina, and they enable vision in dim and dark light conditions. Cones are found mainly in the center part of the retina, and they facilitate the perception of color and visual detail.
In the early stage of retinitis pigmentosa, the rods are affected more than the cones. As these photoreceptors die off, people will notice a progressive narrowing of their visual field. (Visual field refers to the area that you can see when not moving your eyes.) As you lose more and more rods, the cones also begin to deconstruct.
In the late phases of retinitis pigmentosa, as the cones also die, people lose even more of their visual field. Tunnel vision results, and performing everyday tasks becomes a challenge. You may have trouble reading, walking independently, driving, or recognizing objects and faces.
Symptoms of Retinitis Pigmentosa
Typically, the symptoms of RP emerge during childhood. One of the first signs is when a child has trouble moving around in the dark. It may also take an abnormally long time for the child to adapt to different lighting conditions, and bright lights may be uncomfortable. Sometimes, parents mistakenly label the child as clumsy – when really, the problem is that their visual field is restricted.
The genetics of RP vary from patient to patient, and the progression of the disease also varies greatly. Some people experience normal central vision for many years with RP, while others may lose a great deal of vision by early adulthood. Eventually, the majority of people with retinitis pigmentosa will lose most of their eyesight.
Diagnosing Retinitis Pigmentosa
A retinal exam will generally identify this disease. When our eye doctor in Abilene,Texas, performs a comprehensive eye exam, he inspects the retina with the help of high-powered magnification and advanced optometric technology. Abnormal, dark pigment deposits on the retina may indicate RP.
Other procedures used to diagnose RP include:
- Visual Field Testing: to analyze the extent of vision loss
- Electroretinogram (ERG): this device measures the electrical activity of photoreceptors; people with RP have decreased electrical activity, which reflects the diminishing function of the photoreceptors
- Genetic testing: sometimes, a DNA test is used to provide a genetic diagnosis. This procedure provides information about the progression of a patient’s specific form of RP.
Treatment for Retinitis Pigmentosa
Low Vision Services are the primary way in which RP is treated. Unfortunately, RP is an incurable disease. Having the loss of night-vision, peripheral vision, or any other part of vision can be a very difficult and traumatic experience. There is a sense of loss of independence. One can’t drive, watch TV, see their family and friends normally, or do general household activities.
Our Low Vision services include visual aids and strategies to make the most of your remaining vision. Dr. Larry M. Chism is one of only 35 eye care professionals worldwide who is a fellow of the International Academy of Low Vision Specialists. If you have retinitis pigmentosa, our eye doctor in Abilene, Texas, will work with you patiently to help you regain your ability to perform many daily activities, such as reading, watching TV, and driving.
Typically, we like to fit our patients with telescopic lenses or reversed telescopic lenses. The telescopes lenses are small telescopes that are placed on the lens and, just like a binocular, enlarge the objects in the vision path. However, the field of vision will be smaller. A reverse telescopic lens is just like holding binoculars backwards. Objects will be smaller but field vision is greater, giving the patient a larger area of mobility because they see more of their surroundings.
There are also a number of magnifiers or readers that can be used to help magnify text so patients can read.
Recent research indicates that taking supplements of vitamin A may slow the progression of RP in adults. Consult with your eye doctor about whether this therapy is right for you or your child.
Also, a new artificial vision device called the Argus II has been able to restore vision to some people with late-stage RP. This prosthetic device works in place of lost photoreceptors. While it cannot fully restore normal vision, the Argus II can enable patients with RP to read large print and maneuver around without use of a guide dog or cane.
Gene therapy for retinitis pigmentosa is currently showing promise in laboratory studies as a way to prevent vision loss and regain eyesight. Presently, many scientific developments to treat retinitis pigmentosa are on the horizon.
Give us a call at 1-888-243-2020 so we can discuss the best solution for your or your loved one to help them regain their independence.