Retinitis Pigmentosa
Retinitis pigmentosa is a rare genetic disorder that causes the rod and cone cells of the retina to deteriorate. Retinitis pigmentosa is a member of a group of inherited retinal diseases that is characterized by a loss of visual field, night blindness and color perception. This condition is caused by a genetic mutation that runs in families and is not caused by environmental factors, trauma or infection. Retinitis pigmentosa is not preventable.
The retina contains a combination of cells that are known as rods and cones. Rod cells are responsible for night and peripheral vision, also known as side vision. Rod cells can be found throughout the retina with the exception of the fovea. Rod cells are affected more by retinitis pigmentosa than cone cells. Cone cells are responsible for central and color vision. Cone cells exist throughout the retina and the macula, but are concentrated in the fovea, the center of the retina, which has the greatest number of cones.
Symptoms of Retinitis Pigmentosa
Signs and symptoms of retinitis pigmentosa may begin to become apparent between 10 and 30 years of age. Some of these symptoms may include the following.
- Night blindness or a decrease in night vision
- Loss of peripheral vision
- Loss of central vision
- Loss of visual acuity
- Loss of the perception of color
Diagnosis of Retinitis Pigmentosa
Retinitis pigmentosa is a rare disorder and difficult to diagnose accurately. It is usually diagnosed during early to middle childhood. The diagnosis of retinitis pigmentosa is made after an examination of the eyes and the following diagnostic tests:
- Fluorescein angiography
- Fundus photography
- Slit-lamp examination
- Visual acuity test
- Visual field testing
- Ophthalmoscope examination
- Electroretinogram, or ERG
Treatment of Retinitis Pigmentosa
While there is no cure for retinitis pigmentosa there are several treatment options available that will help patients with their disorder.
Non-surgical Treatments
One option is to work closely with a low vision specialist to access low vision therapy aids and assistive devices that will help to maintain independence. Another non-surgical option in the treatment of retinitis pigmentosa is the use of dietary supplements containing antioxidants that may slow the progression of the disease and its associated loss of vision.
Clinical Trials
During Phase I of clinical trials, genetic therapy has proved to be successful in restoring some vision in children and young adults affected by a severe form of retinitis pigmentosa known as Leber congenital amaurosis, or LCA.
In Phase II of clinical trials, valproic acid has been shown to slow the progression of visual loss and preserve or restore vision for those patients with Autosomal Dominant Retinitis Pigmentosa (RP), a form of retinitis pigmentosa.
Surgical Treatments
A surgical treatment option, recently been approved by the FDA, is an epiretinal prosthesis known as the Argus II Retinal Prosthesis System. It is an implanted medical device that stimulates the inner cells of the retina causing signals to be transmitted through the optic nerve to the visual cortex. It has restored some functional vision in those select patients affected with retinitis pigmentosa.