Subretinal electronic chips allow blind patients to read letters and combine them to words.
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 electrodes allows light-independent direct stimulation and testing of the neuron-electrode interface. Visual scenes are projected naturally through the eye's lens onto the chip under the transparent retina. The chip generates a corresponding pattern of 38 × 40 pixels, each releasing light-intensity-dependent electric stimulation pulses. Subsequently, three previously blind persons could locate bright objects on a dark table, two of whom could discern grating patterns. One of these patients was able to correctly describe and name objects like a fork or knife on a table, geometric patterns, different kinds of fruit and discern shades of grey with only 15 per cent contrast. Without a training period, the regained visual functions enabled him to localize and approach persons in a room freely and to read large letters as complete words after several years of blindness. These results demonstrate for the first time that subretinal micro-electrode arrays with 1500 photodiodes can create detailed meaningful visual perception in previously blind individuals.
Centre for Ophthalmology, University of Tübingen, Schleichstr. 12, 72076 Tübingen, Germany. ezrenner@uni-tuebingen.de
Eberhart
E
Zrenner
Karl Ulrich
KU
Bartz-Schmidt
Heval
H
Benav
Dorothea
D
Besch
Anna
A
Bruckmann
Veit-Peter
VP
Gabel
Florian
F
Gekeler
Udo
U
Greppmaier
Alex
A
Harscher
Steffen
S
Kibbel
Johannes
J
Koch
Akos
A
Kusnyerik
Tobias
T
Peters
Katarina
K
Stingl
Helmut
H
Sachs
Alfred
A
Stett
Peter
P
Szurman
Barbara
B
Wilhelm
Robert
R
Wilke
D000328:Adult; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D020007:Implants, Experimental; D008027:Light; D008297:Male; D011932:Reading; D012160:Retina / Q000601:surgery*; D058499:Retinal Dystrophies / Q000601:surgery*; D012682:Sensory Aids; D014796:Visual Perception / Q000502:physiology*