RETINITIS PIGMENTOSA

Researchers Present Hopeful Research Findings at ARVO 

Dr. Alan Chow of Optobionics, a biotechnology company based in Chicago, presented preliminary findings indicating that six patients who are blind from retinitis pigmentosa and Usher syndrome experienced visual responses from a microelectronic prosthetic device implanted in the eye. These unpublished findings-from a phase one clinical trial testing the safety of the company's Artificial Silicone Implant (ASR)-were presented for the first time at the annual meeting of the Association for Research and Vision in Ophthalmology (ARVO) held in Ft. Lauderdale, Florida.

Retinal prosthetic devices might one day restore ambulatory vision to patients who are blind from retinal degenerative diseases, allowing them to regain their mobility and independence. In the Optobionics study, six blind or severely visually-impaired patients reported being able to perceive a brightened visual field in the area of the retina where the device was implanted. Some patients also reported being able to perceive crude forms and movement.

Dr. Gerald Chader, Chief Scientific Officer of The Foundation, attended the ARVO presentation and stated, "It is very encouraging that patients in the safety study have not experienced complications. It is even more exciting to hear subjective reports from the patients that they could perceive light and forms. However, until the complete study findings are published in a peer-reviewed medical journal, it is difficult for the scientific community to comment."

The Optobionics device, called an Artificial Silicon Implant (ASR), was first implanted in three patients in June of 2000. Three more patients received the device in July of 2001. The ASR is 2 millimeters in diameter and one thousand of an inch in thickness, making it thinner than a human hair. It contains 3500 solar cells that are designed to convert light into electrical signals. The device is designed to function in place of diseased photoreceptor cells, transmitting light to the remaining nerve cell network in the retina. 

Drs. Mark Humayun and Eugene de Juan of the Doheny Retina Institute at the University of Southern California (USC) presented similar findings from one patient involved in a phase one clinical trial. The USC group recently began testing a retinal prosthetic device they conceived and pioneered. The prototype used in this clinical trial was then further developed and refined by Second Sight, LLC of Valencia, CA. The prosthesis measures 4 millimeters by 5 millimeters, and contains 16 electrodes in a 4-by-4 array.

The Second Sight prosthesis receives electronic signals captured by a small camera mounted on a pair of glasses. The images are transmitted to the prosthesis via a receiver implanted behind the ear. In the initial phases of this trial, the device will only be turned on when the patient is under medical supervision.

Commenting on the project, Dr. Humayun said, "The Foundation Fighting Blindness provided crucial funding support in the early phases of this research. Their early and continued support helped make this clinical trial possible."

The retinal prosthesis is one of several exciting breakthroughs in the treatment of retinal degenerative diseases. Gene therapy also shows promise in restoring lost vision. With safe drug delivery methods, several drug therapies could prevent vision loss. The arsenal of potential treatments is growing. With your help, there is a cure in sight.

If you are patient of retinitis pigmentosa and want to know more about latest in this field you can subscribe by sending a blank message to blindness-on@mail-list.com  or visit their website http://www.blindness.org