Nov. 3, 2010 Research published in Proceedings of the Royal Society B reveals that a group of researchers based in Germany have developed a retinal implant that has allowed three blind people to see shapes and objects within days of the implant being installed.
One blind person was even able to identify and find objects placed on a table in front of him, as well as walking around a room independently and approaching people, reading a clock face and differentiating seven shades of grey. The device, which has been developed by the company Retinal Implant AG together with the Institute for Ophthalmic Research at the University of Tuebingen, represents an unprecedented advance in electronic visual prostheses and could eventually revolutionise the lives of up 200,000 people worldwide who suffer from blindness as a result of retinitis pigmentosa, a degenerative eye disease.
In this disease light receptors in the eye cease to function. Writing in Proceedings of the Royal Society B, Prof. Dr. Eberhart Zrenner (founding Director of Retinal Implant AG and Director and Chairman of the University of Tuebingen Eye Hospital) states that "The results of this pilot study provide strong evidence that the visual functions of patients blinded by a hereditary retinal dystrophy can, in principle, be restored to a degree sufficient for use in daily life."
The device -- known as a subretinal implant -- sits underneath the retina, directly replacing light receptors lost in retinal degeneration. As such, it uses the eyes' natural image processing capabilities beyond the light detection stage to produce a visual perception in the patient that is stable and follows their eye movements. Other types of retinal implants -- known as epiretinal implants -- sit outside the retina and because they bypass the intact light-sensitive structures in the eyes they require the user to wear an external camera and processor unit.
The subretinal implant described in this paper achieves unprecedented clarity because it has a great deal more light receptors than other similar devices. As Prof. Dr. Zrenner states, "The present study...presents proof-of-concept that such devices can restore useful vision in blind human subjects, even though the ultimate goal of broad clinical application will take time to develop."
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- Eberhart Zrenner, Karl Ulrich Bartz-Schmidt, Heval Benav, Dorothea Besch, Anna Bruckmann, Veit-Peter Gabel, Florian Gekeler, Udo Greppmaier, Alex Harscher, Steffen Kibbel, Johannes Koch, Akos Kusnyerik, Tobias Peters, Katarina Stingl, Helmut Sachs, Alfred Stett, Peter Szurman, Barbara Wilhelm, Robert Wilke. Subretinal electronic chips allow blind patients to read letters and combine them to words. Proceedings of the Royal Society B, 2010; DOI: 10.1098/rspb.2010.1747
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