Visually impaired or blind patients with degenerative retina conditions would be very happy if they were able to regain mobility, find their way around, be able to lead an independent life and to recognize faces and read again. These wishes were documented by a survey conducted by a research team ten years ago to find out what patients' expectations of electronic retina prostheses (retina implants) were.
Today these wishes look set to become reality, as the presentations to be given at the international symposium "Artificial Vision" on 19 September 2009 at the Wissenschaftszentrum Bonn demonstrate. The symposium is being staged by the Retina Implant Foundation and the Pro Retina Stiftung zur Verhütung von Blindheit (Pro Retina Foundation for the Prevention of Blindness), a foundation of the patients' organization Pro Retina Deutschland e.V.
Scientists have been working on developing retina prostheses for more than twenty years now. Research has been conducted particularly intensively in Germany, where scientists and patients have worked in tandem and have succeeded in obtaining government funding. "Back then we didn't want high-tech just for space and defence programs but finally high-tech for people as well," Professor Rolf Eckmiller, a neuro-informatics specialist at the University of Bonn and a pioneer in the field, recalls.
This investment is now bearing fruit. The German research consortiums lead the field in this area of research. Three of the four research teams presenting their findings in Bonn are from Germany.
As the presentations show, all the electronic retina prostheses convey visual impressions, so-called phosphenes. Patients participating in a US study were able to distinguish light and dark and to register movement and the presence of larger objects. In addition, early reports from a project being conducted by a German research group led by Profesor Eberhart Zrenner at the University of Tübingen indicate that restoring visually impaired patients' ability to read is not just wishful thinking. Some patients are able to read letters if these are eight centimetres high.
"We're in the final run-up," explains Professor Peter Walter from the University Eye Clinic in Aachen. Walter is scientific director of the symposium "Artificial Vision." "The final studies prior to market launch have begun or are set to begin," he says in his latest progress report. These studies are designed to test the long-term tolerability of the retina implants and their benefits in everyday life. The manufacturers expect the implants to be approved in 2011.
Naturally, there is a lot of interest among patients in the new products. "Compared with the study we conducted ten years ago, patients now have a much clearer idea [of what they expect from retina prostheses]," says Helma Gusseck, chairperson of the Stiftung Retina-Implantat (Retina Implant Foundation). Gusseck, who also chairs the Pro Retina Stiftung, suffers herself from Retinitis pigmentosa, a degenerative retina condition and can now only distinguish between light and dark. For her the research findings are a relief: "You can, so to speak, go blind without worrying about it, because you know that the systems will soon be ready and we therefore have an option."
Nevertheless, this is really only the beginning. "What we're seeing is different systems racing to compete," says Peter Walter. In one of the systems - the sub-retinal implant - the chip is implanted under a layer of nerve cells in the retina. There, like the photoreceptors in the retina, it receives light impulses, converts these into electrical signals and transmits them to the nerve cells of the retina. The retina prosthesis developed by Professor Zrenner's team in Tübingen and that developed by a US team led by Joe Rizzo and Shawn Kelly at the Boston Implant Project in Cambridge, Massachusetts, work according to the same principle.