Understanding Retinitis Pigmentosa
Retinitis pigmentosa (RP) is an inherited disorder of the eyes that causes retinal degeneration. The retina is the light sensitive area at the back of the eye. The retina has photoreceptor cells made up of rods and cones that are located in the back of the eye. Retinitis pigmentosa is responsible for the breakdown of these photoreceptor cells, which causes gradual peripheral vision loss.
This disease affects one in 4,000 people in the United States and Europe, which makes it one of the most common inherited diseases of the retina. The Foundation Fighting Blindness states there are approximately 100,000 people in the United States with retinitis pigmentosa.
There is a group of related conditions that cause retinitis pigmentosa. They include: Leber’s congenital amaurosis, Usher syndrome, Bardet-Biedl, rod-cone disease, Refsum disease and others.
1. Initial Symptoms of Retinitis Pigmentosa
RP is typically initially diagnosed in an individual when they are between ten and 30 years. An earlier onset of this disease usually indicates a more severe form of RP. The most common initial symptom is night blindness (nyctalopia), which means decreased vision at night or in poor light. Often a person may notice that it takes a progressively longer time for their eyes to adjust to the light when they move into a darker area from a brighter one.
This occurs when the rods of the retina are affected first by this disease. Normally, the rod photoreceptors are responsible for black and white vision, while the cone receptors are responsible for color vision.
2. First Symptoms when the Cones are Affected
When the disease affects the cones of the retina first, people will experience the gradual loss of central vision. They will also lose the ability to distinguish color.
3. Tunnel Vision as More Rods Breakdown
As this disease progressively attacks the rods, the cells breakdown and causes the patients to lose their peripheral vision (tunnel vision). It is common for patients to maintain clear central vision throughout their lives, but they lose a ring of vision in their peripheral visual area. The ring pattern of visual loss is called ring scotoma. Some people have compared their vision to looking through a straw.
Signs of ring scotoma would be tripping over an object that was in the pathway but not in the visual field. This is often a symptom that is not recognized initially, but this defect may be recognized during a test for a driver’s license or if the person was in a car accident.
4. Retinitis Pigmentosa Beginning in the Central Area
One type of RP causing loss of vision is called macular dystrophy, which begins in the central area rather than the peripheral area. Patients are unable to focus on any detailed work or focus on a single object.
5. Flashes of Light
Another common symptom is concentric waves of lights. Quite often patients will have a sensation of twinkling or flashes of light, which they describe as small shimmering or blinking lights, called photopsia.
6. Usher Syndrome
Another symptom associated with RP is hearing loss. Approximately 10 to 30 percent of patients with retinitis pigmentosa have associated hearing loss. Some people will also have severe balance problems with this disorder.
7. Leber’s Amaurosis
Leber’s amaurosis is a more severe form of RP as children may have very reduced vision at birth, or they may be completely blind within the first six months of life. Parents will often notice a lack of response to visual stimuli, and the babies will also have roving eye movements, called nystagmus. These children will often press on their eyes with their fists or fingers.
If you recognize any of these visual symptoms in yourself or a loved one, seek out a heath care provider for evaluation. As this disease progresses slowly, it is easy to ignore some of the symptoms at first, but earlier treatment of any disease is always a good idea.