The medical technology company Retina Implant AG from Reutlingen has developed an electronic chip which is implanted in the eye under the retina, giving many blind people part of their sight back. At the end of 2005 two patients who had been totally blind beforehand were operated on successfully. The scientists at Retina Implant are developing the retina implants initially for patients with retinitis pigmentosa, a major disease which over the course of a lifetime leads to complete sight loss. At the heart of the development is a silicon chip with tiny photo-sensors. The sensors are responsible for controlling an electronic switch which – depending on the degree of brightness – electrically stimulates the nerve cells of the retina to a greater or lesser extent.