Scientific American article discusses the promise of emerging technologies to successfully stimulate retinas ravaged by retinitis pigmentosa or age-related macular degeneration.
Scientists have been working for decades to create an optical prosthesis that restores at least partial vision to those suffering from retinitis pigmentosa, macular degeneration and other retina-damaging diseases. Some retinal implants have begun to deliver on that promise, but the challenge remains for researchers to develop a technology that, in addition to providing clear images, can be worn comfortably over the long term.
Germany’s Retina Implant, AG, thinks it has made great strides in both areas, an assertion that will be put to the test later this year when the company launches its phase II human clinical trial, placing subretinal (under retina) implants in about 50 patients over the next few years. Meanwhile, Sylmar, Calif.–based Second Sight Medical Products plans to make its epiretinal (over retina) implants commercially available in Europe later this year. Researchers at the Massachusetts Institute of Technology and other institutions and medical technology companies are likewise developing retinal implants—the retina lines the eye’s inner surface and records images in patterns of light and color—but are not as far along as Retina Implant or Second Sight.
Retina Implant’s device is a three- by three-millimeter microelectronic chip (0.1 millimeter thick), containing about 1,500 light-sensitive photodiodes, amplifiers and electrodes that is implanted directly under the retina to generate artificial vision by stimulating inner retina nerve cells. The chip, which is placed in the retina’s macular region, absorbs light entering the eye and converts it into electricity that stimulates any still-functioning retinal nerves. This stimulation is relayed to the brain through the optical nerve.