At a Glance
The Early Symptoms
The late Symptoms
Retinitis Pigmentosa: What Is It?
Retinitis pigmentosa is a group of genetic disorders that are rare and involve retina cells that have broken down. The retina is the tissue that is located at the back of the eye and is sensitive to light. Some of the most common symptoms of RP include problems with night vision and a loss of peripheral vision (side vision).
How Common Is Retinitis Pigmentosa?
RP is a rare genetic disorder. While current statistics aren’t available, it’s typically estimated that about one in 4,000 individuals are affected across the world.
What Causes Retinitis Pigmentosa?
RP is a disorder that is inherited and is a result from harmful changes in any number of more than 50 different genes. It is these genes that hold the instructions for creating the proteins that are necessary in the cells in the retina known as the photoreceptors. Some of these changes, which are called mutations, in the genes are so serious that the genes are unable to create the necessary protein and limits the function of the cells. Some other mutations can produce a protein that can be incredibly toxic to the cell. There are other changes that may result in an abnormal protein that does not properly function. In all of these instances, the outcome is damage to the photoreceptors.
What Exactly Are Photoreceptors?
Photoreceptors are the cells that are located in the retina that start the process of being able to see. These cells absorb light and change it into electrical signals, which are then sent to other cells within the retina and through the optic nerve and to the brain where they are then processed into the various images that we are able to see. There are ultimately two basic kinds of photoreceptors that are known as cones and rods. Cones generally are found in the center part of the retina and allow you to perceive fine detail and color, while rods are found in the outer sections of the retina and allow you to view details in dim and dark environments.
How Is Retinitis Pigmentosa Inherited?
To comprehend how you inherit RP, you need to familiarize yourself a bit more with genes and how they’re passed down to children from parents. Genes will bundle together on structures known as chromosomes. Every cell in the body contains 23 different pairs of chromosomes. There is a copy of every chromosome that is passed at conception by a parent through sperm and egg cells. The X and Y chromosomes, which are also referred to as sex chromosomes, determine whether an individual is born as a male or a female. The other 22 paired chromosomes, which are known as autosomes, contain the bulk majority of genes that will determine the non-sex traits. Retinitis pigmentosa can be inherited in one of three different ways:
Autosomal Recessive Inheritance
With autosomal recessive inheritance, it will take two copies of the changed gene in order for the disorder to occur. A person with a recessive gene mutation is considered a carrier. When there are two carriers of this gene mutation and they have a child, then there is a:
Autosomal Dominant Inheritance
With this particular inheritance pattern, it is only a single copy of the gene with the disease-causing mutation that can cause the disorder to develop. When one of the parents has the dominant gene mutation, there is a one in two chance that children may inherit the mutation as well as the disorder.
With this type of inheritance, mothers will carry a mutated gene on an X chromosome and can pass it on to their sons. Due to the fact that females have two X chromosomes, the impact of a mutation on just one X chromosome will be offset by the normal gene on the other one. So, if a mother is a carrier, there will be a:
What Are the Symptoms of Retinitis Pigmentosa?
In the early stages of this disease, rods tend to be far more severely impacted than cones. As each rod dies off, individuals will begin to experience night blindness as well as a progressive loss of their visual field, which is the area of space visible at any given moment without eye movement. Eventually, the loss of rods will result in the breakdown of cones, as well as their loss. During the late stages of the diseases, the cones will die and individuals will begin to lose more of their visual field, resulting in the development of tunnel vision. Individuals may find it difficult to perform basic day-to-day tasks like walking with no assistance, driving, reading, and recognizing objects and faces.
How Does Retinitis Pigmentosa Progress?
The symptoms of this disease tend to appear in childhood. Child find it difficult to navigate through the dark. It may also take an unusually long time to adjust to lighting changes. As the visual field gets more restricted, individuals tend to trip over things and come off as clumsy. Individuals with RP tend to find bright lights uncomfortable, which is a condition referred to as photophobia. Due to the fact that there are numerous gene mutations that cause this disorder, its progression can differ from one person to the next. Some individuals will retain their central vision as well as a restricted visual field well into their 50s, while other individuals will experience considerable loss of vision during early adulthood. However, eventually, most people with retinitis pigmentosa will lose the majority of their eyesight.
How Do Physicians Check for Retinitis Pigmentosa?
RP is diagnosed partially through a retina examination. An eye doctor will utilize an ophthalmoscope, which is a tool that will allow for a clearer and wider view of the retina. This generally reveals an abnormal and dark pigment deposit that streaks the retina. Deposits like these are partly why RP received its name. Some of the other tests for this disease include the following:
What Is the Treatment for Retinitis Pigmentosa?
Living with Loss of Vision
There are a many devices and services available to assist individuals who have lost their vision to carry out daily tasks and maintain their sense of independence. Aside from an eye doctor, it is important to have assistance from a team of specialists like occupational therapists, certified low vision therapists, mobility specialists, and others.
Children who have RP may benefit from certain low vision aids that enhance their existing vision. For instance, there are specialized lenses that can magnify your central vision to eliminate glare and expand your visual field. There are various computers programs that area designed to read text. There are also closed-circuit televisions that have cameras that are able to adjust text to suit a person’s vision. There are event portable lighting devices that are designed to adjust to dim or dark environments. Mobility training is able to teach individuals to use a guide dog or cane, while eye scanning techniques can assist individuals with the optimization of their remaining vision. As soon as a child receives their diagnosis, he or she will be referred to a specialist for a comprehensive examination. In addition, parents may want to schedule a consultation with the school administrator and teachers to ensure that appropriate accommodations are put into place.
For parents of children with the condition, one particular challenge is determining when the child may need to learn to utilize a guide dog or cane. Undergoing routine eye exams to measure the progression of RP will assist parents in making well-informed decisions regarding the appropriate rehabilitation and services.
Targeted Therapies for Retinitis Pigmentosa
A clinical trial sponsored by NEI discovered that 15,000 international units of vitamin A palmitate on a daily basis modestly slowed the progress of RP in adults. Due to the fact that there are numerous forms of the disease, it is hard to foresee the way any one patient will actually respond to the treatment. Speak to an eye doctor to determine whether taking vitamin A is the right thing for you and/or your child.
The Argus II, which is an artificial vision device, has shown to be promising for restoring some level of vision in individuals who are in the late stages of RP. Argus II is a prosthetic device and functions in the place of photoreceptor cells that have been lost. The device entails a light-sensitive electrode that is implanted on the retina via a surgical procedure. A pair of eyeglasses with a camera attached transmits signals wirelessly to the electrode, and these signals are relayed to the brain. While the device is unable to restore normal vision, it has allowed individuals with RP to navigate environments with a guide dog or cane and read large letters with the Argus II device. In 2012, the U.S. FDA provided a humanitarian device exemption so that late-stage RP could be treated by the Argus II device, which means that it has not proven to be effective, but the FDA has determined that the potential benefits of the device outweigh its risks.
If you would like to learn more, contact us at Performance Vision Inc.