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Visual prostheses such as subretinal implants are intended for electrical multisite excitation of the retinal network. To investigate relevant issues like spatial resolution and operational range, we have developed an in vitro method using microelectrode arrays to stimulate isolated retinae. Ganglion cell activity in the chicken retina evoked by distally(More)
A light-sensitive, externally powered microchip was surgically implanted subretinally near the macular region of volunteers blind from hereditary retinal dystrophy. The implant contains an array of 1500 active microphotodiodes ('chip'), each with its own amplifier and local stimulation electrode. At the implant's tip, another array of 16 wire-connected(More)
There are presently several concepts to restore vision in blind or highly visually handicapped persons by implanting electronic devices into the eye in order to partially restore vision. Here, the approach to replace retinal photoreceptors by a subretinally implanted microphotodiode array (MPDA) is summarized. A survey is given on the present state of the(More)
Automats for patch clamping suspended cells in whole-cell configuration must (1) bring isolated cells in contact with patch contacts, (2) form gigaseals, and (3) establish stable intracellular access that allows for high quality recording of ionic currents. Single openings in planar substrates seem to be intriguing simple solutions for these problems, but(More)
Subretinal implants intend to replace photoreceptor function in patients suffering from degenerative retinal disease by topically applying electrical stimuli from the subretinal space. This study intended to prove the feasibility of a newly developed transchoroidal surgery and, furthermore, of a subretinal electrode array, which closely resembles envisioned(More)
The idea of implanting microphotodiode arrays as visual prostheses has aroused controversy on its feasibility from the moment it appeared in print. We now present results which basically support the concept of replacing damaged photoreceptors with subretinally implanted stimulation devices. Network activity in degenerated rat retinae could be modulated(More)
Electrical stimulation has been shown to have neuroprotective effects on ganglion cells and photoreceptors in axotomized and dystrophic retinas from Royal College of Surgeons (RCS) rats. This study determined whether electrical stimulation also has a neuroprotective effect on cells in the inner nuclear layer (INL) of retinas. We cultivated retinas from(More)
Retinaimplantate sollen durch elektrische Stimulation der Retina bei blinden Patienten mit teilweise degenerierter Netzhaut (z. B. bei Retinitis pigmentosa) Seheindrücke erzeugen. Voraussetzung hierfür ist, dass die in der Retina elektrisch erzeugten Aktivitätsverteilungen auch korrekt in der Sehrinde abgebildet werden, so dass Form- und Bewegungssehen(More)
Electrical activity of electrogenic cells in neuronal and cardiac tissue can be recorded by means of microelectrode arrays (MEAs) that offer the unique possibility for non-invasive extracellular recording from as many as 60 sites simultaneously. Since its introduction 30 years ago, the technology and the related culture methods for electrophysiological cell(More)
PURPOSE The perception of 11 persons blinded by hereditary retinal degeneration elicited by a subretinally implanted 16-electrode array used for light-independent direct stimulation of the retina is described. This device is part of the Tübingen retina implant, which also employs a light-sensitive, multiphotodiode array (MPDA). The ability to reliably(More)