Implant restores visual perception in blind patients

A subretinal implant has been shown to restore some vision in patients blinded by hereditary retinal degeneration according to a study published in the Proceedings of The Royal Society B.

The subretinal micro-electrode arrays with 1500 photodiodes was shown to improve visual function from a state of complete blindness enabling recognition of objects up to letters and words..

The research, led by Dr Eberhart Zrenner et al. from the University of Tübingen, was a clinical pilot study examining the efficacy of a light sensitive, externally powered microchip implanted subretinally in three patients with hereditary blindness. The implant contains an array of 1500 active microphotodiodes that each have an amplifier and local stimulation electrode. In addition to this, the tip of the implant contains a further 16 wire-connected electrodes that allow light-independent direct stimulation and testing of the neuron–electrode interface.

Naturally, images are projected through the eye and onto the microphotodiodes through the retina. There was a corresponding pattern produced by the implant sending light-intensity dependent electric stimulation pulses to the patient.

The results demonstrated strong evidence towards the ability of the implant to improve the patient’s visual functions allowing the three patients involved to locate bright objects on a dark table. One patient could even correctly describe and name the shapes as well as finding and approaching persons within a room and reading large letters as complete words.