Retinitis pigmentosa (RP) is an inherited condition that causes vision loss.
RP affects the light-sensitive tissue lining the back of the human eye, known as the retina. Light brings visual information about the world into the eye through the pupil. Light then strikes the retina, where special photoreceptor cells convert the visual information into electrical pulses. The optic nerve then carries these pulses to the brain, which recognizes the pulses as images.
Retinitis pigmentosa affects how the retina responds to light. There are two types of photoreceptor cells in the retina: rods that detect dim light and cones that detect light and color. Most forms of RP start with the breakdown of rods; degeneration of the rods lead to night blindness.
Causes of Retinitis Pigmentosa
RP is not the result of infections, injuries or other external or environmental cause. Retinitis pigmentosa is a genetic condition, passed down through families. The National Human Genome Research Institute says that most cases are the result of recessive genes, so a person with RP inherited the gene from both parents. In some cases, though, someone with retinitis pigmentosa inherits the gene from only one parent. In still other circumstances, a new mutation causes RP in someone who does not have a family history of the condition.
Scientists think several different types of gene mutations, or changes in the genes, may send faulty messages to the photoreceptor cells of the retina. These flawed messages eventually cause the retina to breakdown; the degeneration of these cells causes vision loss.
Signs and Symptoms of Retinitis Pigmentosa
Symptoms of RP often begin in childhood. People with the condition tend to lose their vision slowly over the course of years. The type of vision loss and the speed at which vision loss occurs varies from person to person, depending on the form of their condition and other factors. The condition does not usually cause total blindness.
Loss of night vision
RP may cause night blindness, which makes it hard to see in low light. People with retinitis pigmentosa may have trouble seeing in movie theaters or other dim rooms. Driving at dusk or at night may be especially difficult. Many people with RP have normal vision during the day. They may find it takes longer for their eyes to adjust to darkness once they start losing their night vision.
Gradual loss of peripheral vision
People with RP may have “tunnel vision,” which means they do not see well to the sides when looking straight ahead. Loss of this side vision can cause someone to bump into things.
Loss of central vision
Some people with RP experience loss of central vision, which makes it hard to do detailed tasks, such as reading or threading a needle.
Problems with color vision
Those with retinitis pigmentosa may have trouble seeing different colors.
Support and Aids
There is no cure for retinitis pigmentosa, but treatment can help control symptoms and reduce complications of the condition.
Doctors can use genetic testing to determine if patients have the genes associated with RP. Doctors use a test known as electroretinography to measure electrical activity in the retina to determine how well it responds to light. Visual field testing determines if RP has affected peripheral vision. Optical coherence tomography (OCT) takes highly detailed pictures of the retina to diagnose and assess the progression of RP.
Researchers have not yet established a single course of treatment for retinitis pigmentosa, but are working to determine why RP occurs in some families and are hoping to develop treatments based on what they learn. Taking vitamin A palmitate may help some people with RP, according to the American Academy of Ophthalmology.
Low vision aids can help people with retinitis pigmentosa make the most of their remaining sight. Some low vision aids, such as eSight, use high tech cameras, high-resolution screens, and smart algorithms to create clear, real-time images. The combination of cameras, algorithms and high-res screens enhances peripheral and central vision in people with retinitis pigmentosa.
Did you find this article interesting? Learn about Richard Jablonski, a U.S. Veteran living with Retinitis Pigmentosa.