Retina Implant Chip Makes 11 Blind People See Again

A clinical study with a German retinal implant chip successfully demonstrated the artificial restoration of vision with this technology for the first time. The light sensitive electronic chip that is implanted under the dysfunctional retina of people who became blind due to disease has an array of 1,500 pixels and stimulates the still existing optic nerves.

Over 15 years of ongoing research activities at the University Eye Hospitals in Tübingen and Regensburg, Germany, in the development of an subretinal implant chip to restore useful vision in patients blind from hereditary retinal degeneration now culminated in showing that the eleven participating and previously blind patients can again perform activities like locating tableware and localize and approach large objects. One patient was able to discern 7 shades of grey, read the hands of a clock and combine the letters of the alphabet to words. This study proves that subretinal microelectrode arrays can create meaningful visual perception and some freedom of movement and orientation in previously blind individuals.

“So far, our approach using subretinal electronic implants is the only one that has successfully mediated images in a trial with freely moving blind persons by means of a light sensor array that moves with the eye,” the scientists said.

“All the other current approaches require an extraocular camera that does not link image capture to eye movements, which, therefore, does not allow the utilization of microsaccades for refreshing the perceived images.”

In most hereditary retinal diseases, such as retinitis pigmentosa, the photoreceptors progressively degenerate, often causing blindness in adult life, and there is no therapy available to treat this disease.

The chip, which is approximately 3mm x 3 mm in size, contains 1,500 independent microphotodiode-amplifier electrode elements and is surgically implanted below the fovea (area of sharpest vision in the retina). It is powered by a sub-dermal coil behind the ear that is powered from a battery via trans-dermal inductive transmission.

It provides a diamond-shaped visual field of 15 degrees diagonally across chip corners.

The implant used in this clinical study is developed since 1995 at the Centre for Ophthalmology, Tuebingen, Germany, lead by Prof. Dr. E. Zrenner who has been testing the subretinal chip in animals for biocompatibility, biostability, safety, and efficacy. The know-how gained by this research and protected by worldwide property rights was transferred to the medical engineering company Retina Implant AG, Reutlingen, now responsible for production, sponsorship of the clinical study, and worldwide distribution of the subretinal implant.

There will be ever more advanced devices available soon to let the blind see again though, since worldwide there are about 20 groups working on the development of electronic devices that are intended to replace lost visual functions of the retina. Besides trials to connect electronic devices in animals directly to the brain or to the optic nerve, the concepts presently applied in patients with retinitis pigmentosa include microelectrode arrays that are positioned epiretinally "on top" of the retina or subretinally beneath the retina. These devices stimulate neurons that are still surviving in sufficient numbers even many years after blindness has developed. In this field, there are currently four ongoing clinical studies from different groups, one in the United States and three in Germany.