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
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.
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 AND SYMPTOMS
•Difficulty seeing dim lighting
•Tendency to trip easily or bump into
objects when in poor lighting
•Gradual loss of peripheral vision
•Loss of contrast sensitivity
•Eye fatigue (from straining
DETECTION AND 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.
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.