May 14, 2012
Prosthesis Could Restore Sight To Those With Degenerative Eye Disorders
Patients who have lost their sight due to some degenerative eye conditions may someday have their vision restored thanks to a new device developed by experts at the Stanford University School of Medicine.
The unit, announced by Stanford on Sunday, is a type of retinal prosthesis that uses miniature cells similar to solar panels, which are surgically installed underneath the retina, along with a special pair of camera-equipped goggles and a pocket computer which processes the information detected from the device.
"The resulting images would be displayed on a liquid crystal microdisplay embedded in the goggles, similar to what's used in video goggles for gaming," the university explains. "Unlike the regular video goggles, though, the images would be beamed from the LCD using laser pulses of near-infrared light to a photovoltaic silicon chip -- one-third as thin as a strand of hair -- implanted beneath the retina“¦ Electric currents from the photodiodes on the chip would then trigger signals in the retina, which then flow to the brain, enabling a patient to regain vision."
The researchers describe their work in Sunday's edition of the journal Nature Photonics.
"It works like the solar panels on your roof, converting light into electric current. But instead of the current flowing to your refrigerator, it flows into your retina," Dr. Daniel Palanker, associate professor of ophthalmology and co-senior author, said in a statement. "The current implants are very bulky, and the surgery to place the intraocular wiring for receiving, processing and power is difficult. The surgeon needs only to create a small pocket beneath the retina and then slip the photovoltaic cells inside it."
The device is being designed to aid those suffering from retinal degenerative diseases such as age-related macular degeneration, the leading cause of blindness in North America, and retinitis pigmentosa, which causes approximately 1.5 million people across the globe to lose their sight each year, the Stanford press release said.
"In these diseases, the retina's photoreceptor cells slowly degenerate, ultimately leading to blindness. But the inner retinal neurons that normally transmit signals from the photoreceptors to the brain are largely unscathed. Retinal prostheses are based on the idea that there are other ways to stimulate those neurons," the school said in their press release, noting that the prosthesis uses near-infrared light because of its longer wavelength.
Palanker and Dr. James Loudin, a postdoctoral scholar, were responsible for co-creating and designing the device, according to the university. Loudin is a first author on the study along with visiting scholar Dr. Keith Mathieson, while Palanker's co-senior author is Dr. Alexander Sher of the Santa Cruz Institute of Particle Physics at UC Santa Cruz. Funding for the research was provided by the National Institutes of Health, the Air Force Office of Scientific Research and Stanford's Bio-X program.