Eye Facts> Eye Diseases
Diseases & Conditions: Retinitis Pigmentosa
Overview
Retinitis
pigmentosa (RP) is a rare, hereditary disease that causes
the rod photoreceptors in the retina to gradually degenerate.
The rods are located in the periphery of the retina and are
responsible for peripheral and night vision. Cones, another
type of photoreceptor, are densely concentrated in the macula.
The cones are responsible for central visual acuity and color
vision. The disease may be X-linked (passed from a mother
to her son), autosomal recessive (genes required from both
parents) or autosomal dominant (gene required from one parent)
trait. Since it is often a sex-linked disease, retinitis
pigmentosa affects males more than females. People with RP
usually first notice difficulty seeing in dim lighting and
gradually lose peripheral vision. The course of RP varies.
For some, the affect on vision may be mild. Others experience
a progression of the disease that leads to blindness. In
many cases, RP is diagnosed during childhood when the symptoms
begin to become apparent. However, depending on the progression
of the disease, it may not be detected until later in life.
Signs & Symptoms
- Difficulty seeing dim lighting
- Tendency to trip easily or bump into objects when in poor lighting
- Gradual loss of peripheral vision
- Glare
- Loss of contrast sensitivity
- Eye fatigue (from straining to see)
Detection & Diagnosis
Retinitis pigmentosa is usually diagnosed before adulthood. It is often discovered when the patient complains of difficultly with night vision. The doctor diagnoses RP by examining the retina with an ophthalmoscope. The classic sign of RP is clumps of pigment in the peripheral retinal called "bone-spicules." A test called electroretinography (ERG) may also be ordered to study the eye's response to light stimuli. The test gives the doctor information about the function of the rods and cones in the retina.
Treatment
There is currently no standard treatment or therapy for retinitis pigmentosa; however, scientists have isolated several genes responsible for the disease. Once RP is discovered, patients and their families are encouraged to seek genetic counseling.
Current Research
Scientists at Johns Hopkins University are developing a micro-computer chip prosthesis called the Multiple-unit Artificial Retina Chipset (MARC). Once implanted in the retina, the chip transmits images to the brain that are captured from a small camera mounted on the patient's glasses. The chip is still in development and is not yet available for widespread use. Doctors continue to search for treatments for RP but have yet to find a cure.
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