Retinitis pigmentosa is a serious eye disease that is generally regarded as hereditary. It causes a gradual loss of vision over a period of years or decades, but rarely produces complete blindness. The retinal rod cells, responsible for night vision, are the most likely to be affected. The cone cells, responsible for color vision, can also be damaged in some cases. The condition gets its name from the characteristic pigmented spots on the retina.
The symptoms include:
1. Decreased vision at night or in poor light
2. Loss of peripheral vision
3. Loss of central vision in advanced cases
There is no cure at present, but research continues into therapeutic options. There are four classes of treatment in clinical trials:
1. Pharmacological. Drugs and supplements include Vitamin A, lutein, omega-3 fatty acids, hyperbaric oxygen, ciliary neurotropic factor and brimonidine tartrate
2. Gene therapy
3. Cell transplantation. This includes bone marrow derived stem cells and encapsulated cell technology implant
4. Neuro-prosthetic devices. These are also called artificial vision or retinal implants
A recent Japanese study reports that visual sensations have been produced in a blind retinitis pigmentosa patient with a surgically implanted direct optic nerve electrode. This is an important step toward development of an artificial eye system.
Researchers at USC School of Medicine in Los Angeles, Calif. report progress in an electronic prosthetic device that uses a miniature video camera mounted on eyeglasses to send visual signals to the brain. In both retinitis pigmentosa and age-related macular degeneration, the retinal photoreceptor cells lose their function, but the secondary neurons remain healthy. Second Sight Medical Products is named as the sponsor of the device furthest along in development. This company provides a web site (see references) that describes their investigational retinal prosthesis.
Volunteers are needed for clinical trials. See your eye doctor if you have a family history of retinitis pigmentosa.
References:
Amy L. Sutton, ed, “Eye Care Sourcebook”, Omnigraphics, 2008.
Clinical trials:
http://clinicaltrials.gov/ct2/results?term=retinitis+pigmentosa
Shintani K et al, “Review and update: current treatment trends for patients with retinitis pigmentosa”, Optometry. 2009 Jul; 80(7): 384-401.
Sakaguchi H et al, “Artificial vision by direct optic nerve electrode (AV-DONE) implantation in a blind patient with retinitis pigmentosa”, J Artif Organs. 2009; 12(3): 206-9.
Chader GJ et al, “Artificial vision: needs, functioning, and testing of a retinal electronic prosthesis”, Prog Brain Res. 2009; 175: 317-32.
Second Sight Medical Products:
http://www.2-sight.com/
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.