Tiny Electronic Implant Simulates Sight
November 5, 2010: New findings from a trial of an electronic chip implanted into the eye to simulate sight were published this week in the November 3rd issue of the Proceedings of the Royal Society (Biological Sciences). The paper offers a detailed description of the outcomes for three patients using a tiny light-sensitive device developed by the German company, Retina Implant AG.
The device is designed to be implanted beneath the retinas of people who have completely lost their sight as a result of retinitis pigmentosa. Once implanted in the eye, the device captures seven images per second and sends electronic pulses to the retina through 1500 tiny needle-like electrodes, to produce visual sensations – essentially substituting for the role of the person’s damaged photoreceptors.
The three people described in the study were able to “see” shapes and objects allowing them to do common tasks like recognizing items in a table setting or interacting with other people in a room. Those interested in this technology can read the full text of this study on the Royal Society’s web pages. A video of one participant is also available from BBC News. This participant was also able to recognize and read large type – although Dr. Eberhart Zrenner, the lead scientist on the study, cautions that reading is not a key objective of their work, which stresses more practical daily tasks.
Future Study of the Electronic Implant
“The publication of our research in the Royal Society's flagship biological research journal solidifies the work our team has done to restore useful vision to retinitis pigmentosa patients,” said Dr. Zrenner. “The results of our first clinical trial surpassed our expectations and reaffirmed that the subretinal placement of the microchip yielded optimal clinical results. With the success achieved during our first clinical trial, we’ve begun work in our second clinical trial and we hope to learn even more.”
This early (Phase 1) trial was done primarily to determine the safety of surgically implanting the devices into the eye. In total it included 11 German patients who have been blind for 13 to 40 years. None of the 11 patients receiving the device suffered any major complications from the procedure – no retinal detachments, major hemorrhages, inflammation or vitreoretinal tractions were reported. In this trial, the patients did not receive the implant permanently; however, the company has recently begun a second trial, which will eventually expand to several European countries, in which participants will receive a permanent implant. The company has also begun planning for trials in North America and Asia.
The company recently posted this Frequently Asked Questions page about the planned trials.
FFB Leadership on Biological Options
This research is one of several possible strategies to replace damaged photoreceptors in the eyes of people who have permanently lost their vision due to retinal degeneration. In Canada, the Foundation Fighting Blindness and the scientists it funds have chosen to focus on biological means of replacing lost photoreceptors, such as the use of stem cells and other ways to replace the damaged cells with live, healthy ones.
"Electronic devices require ongoing maintenance and will, of course, eventually break down and need to be replaced,” says Dr. Bill Stell, FFB Director of Research Programs. “They will likely also be very costly, and the vision that they can achieve will be rudimentary and only in black and white. Of course, some people will find that even with these limitations, surrogate vision with an electronic prosthesis will be preferable to no vision at all. Ultimately, however, we believe that a biological approach will provide a more natural experience of vision and a more pleasing, long-lasting and cost-effective outcome.”
Dr. Gautram Awatramani, a scientist funded by the FFB here in Canada, has been studying the use of a light-sensitive molecule derived from plants to replicate the signals sent by photoreceptors. This molecule makes it possible for surviving retinal nerve cells to capture light at points in the retina that are very close together, allowing them to distinguish fine details and to experience a more nuanced way of seeing. This approach is expected to provide a more natural simulation of vision than electronic prostheses.
Use this link to hear Dr. Awatramani’s description of his work, and to see the slides from his presentation.
Dr. John Flannery at the Donald K. Johnson Eye Centre of Toronto Western Hospital is also working with light-sensing molecules called “photoswitches.” When coupled with the sight-producing proteins of the eye, photoswitches can detect different wavelengths of light and induce light sensitivity in blind mice. The FFB is partnering with the Donald K. Johnson Eye Centre to support sight-restoring research.