The retina implant--new approach to a visual prosthesis.

Currently, no treatment is available for degenerative diseases of retinal photoreceptors. The patients are faced with a high risk of blindness. Biological approaches failed to prove efficacy. A new concept for the treatment of disorders like retinitis pigmentosa is electrical stimulation at various levels of the visual system. Therefore, devices were fabricated with stimulating electrodes contacting retinal or central neurons to elicit biological activity in these cells. It became possible to fabricate even complex devices with an external power supply encapsulated within biocompatible materials. Animal experiments showed that with implanted prototypes cortical activation could be achieved and first experiments in blind human subject also suggest that vision can be restored, however at present in a very low range of simply identifying spots of light. Further developments and also the continuation of animal experiments are necessary before the clinical application will become a standard procedure.