Wireless vision implant

For twelve years, experts from different disciplines in the fields of microelectronics, neurophysics, information engineering, computer science, materials science and medicine have been working to develop a visual prosthetic device for patients who have lost their sight through diseases of the retina.

In September 2007, their effort was rewarded. In a clinical study including six patients, the team was able to demonstrate not only that a completely implantable vision prosthesis is technically feasible and proven functioning, but also that it enables patients to perceive visual images.

“For normally sighted people that may not seem much, but for the Blind, it is a major step,” comments Dr. Hoc Khiem Trieu from the Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Duisburg. “After years of blindness, the patients were able to see spots of light or geometric patterns, depending on how the nerve cells were stimulated.”

Dr. Hoc Khiem Trieu has been involved from the outset of this project, which was funded by the German Ministry of Education and Research. Together with Dr. Ingo Krisch and Dipl.-Ing. Michael Görtz he translated the specifications given by the medical experts and material scientists into an implant and chip design. The scientists are to receive the Joseph von Fraunhofer Prize 2008 for their work.

“A milestone was reached when the prosthetic system finally operated wirelessly and remotely controlled,” explains Dr. Ingo Krisch. “A great deal of detailed work was necessary before the implant could be activated without any external cable connections.” “The designs became smaller and smaller, the materials more flexible, more robust and higher in performance, so that the implant now fits comfortably in the eye,” reports Michael Görtz. The system benefits from a particular disease pattern, and it uses a specific operating principle to restore sight: Suffering from retinitis pigmentosa, the light sensitive cells are destroyed, but the connection of the nerve cells to the brain remains intact.

The scientists have bypassed the defects of the retina by means of a visual prosthesis. The complete system comprises the implant and an external transmitter integrated in a spectacle-frame. The implant system converts the image patterns into interpretable stimulation signals. Data and energy are transferred to the implant by a telemetric link. The nerve cells inside the eye are then stimulatedaccording to the captured images. Those intact cells are innervated by means of three-dimensional stimulation electrodes that rest against the retina like small studs.