Abstract

SA.08.01

The subretinal implant: Results of the first clinical study

Zrenner E.¹, Bartz-Schmidt K.-U.¹, Besch D.¹, Bruckmann A.¹, Gekeler F.¹, Greppmaier U.², Sachs H.³, Stett A.³, Wilhelm B.¹, Zabel E.^1
1Department for Ophthalmology, Tübingen; ²Naturwissenschaftlich Medizinisches Institut (NMI), Reutlingen; ³University of Regensburg Eye Hospital, Regensburg

Objective: The purpose of this study was to examine the sensations that are induced in totally blind patients by means of subretinal electronic implants. The implants consist of a chip (3x3x0.1 mm) carrying 1,500 microphotodiodes, amplifiers and electrodes as well as a stimulating array with 16 electrodes for direct stimulation (DS).
Methods: The chip and the direct-stimulation array DS are positioned on a subretinal polyimid foil and are receiving electric current via a subretinal, transchoroidal wiring.
Results: Direct stimulation of rows, columns or blocks made up of four electrodes enabled most patients to localize sources of light and even to distinguish clearly between vertical and horizontal lines. Under optimal conditions, a sequential stimulation of individual electrodes allowed patients to correctly identify the direction and the pattern of different points. Stimulation of the chip by light permitted patients to have a sensation of light and hence to localize light objects, as e.g. a white plate against a black tablecloth or to find a window and to correctly identify the number of sequentially induced light stimuli. By means of SLO-based micro-perimetry of the chip, individual light dots of 100-400 micrometers could be recognized.
Conclusions: The subretinal electrical stimulation of MPDA’s is able to induce sensations of light in blind patients within a limited framework of spatial, temporal and electrical parameters.

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