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Q. Ren, X. Chai, K. Wu, C. Zhou, C-Sight Study Group; Development of C-Sight Visual Prosthesis Based on Optical Nerve Stimulation With Penetrating Electrode Array. Invest. Ophthalmol. Vis. Sci. 2007;48(13):661.
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© ARVO (1962-2015); The Authors (2016-present)
The C-Sight (Chinese Project for Sight) is the first multidisciplinary research project on visual prosthesis funded by the Ministry of Science and Technology of China. This study is to describe the overall design principle, the technological development, and the experimental study of the device.
The C-Sight visual prosthesis is based on optical nerve stimulation with penetrating electrode array. The electrical evoked potential (EEP) with single and multi-electrode array were studied on the rabbit model. Electrical stimulations of different temporal-spatial patterns with the penetrating array were applied to the optic nerve to investigate the EEP responses. A home-made18-channel recording array was implanted to record the responding activities of rabbit visual cortex. An implantable CMOS based micro-camera was developed for the image acquisition and was tested for long-term biocompatibility on rabbit model. In order to evaluate the phosphene position induced by visual prosthesis after implantation on blind people, a tactile based phosphene positioning system (PPS) was developed and studied by the normal sited volunteers with the head mounted display to simulate the induced phosphene.
EEPs were recorded by biphasic current stimulation of the optic nerve using penetrating single electrode and multi-electrode array. Threshold charge density was 35.9µC/cm2 with our electrode, which was lower than the safe limit value for chronic implantation and the previously reported optic nerve prosthesis by surface electrode. The spatial distributions of active intensity in rabbit visual cortex were remarkably different when adjusting the parameters of stimulating patterns and the penetrating site on optic nerve. Micro-camera implanted into the rabbit eye after long-term biocompatibility test demonstrated a good imaging quality. For the phosphene positioning system, our study demonstrate that the accuracy with tactile guided disc is remarkably increased compared to the one without. Positioning of phosphenes in near visual field is more accurate than in far visual field.
The working principle of C-Sight visual prosthesis with stimulating electrode penetrating into optic nerve has been validated on animal experiment. The implantable micro-camera can be employed in the visual prosthesis. Our proposed phosphene positioning system with tactile guided disc can be used to evaluate the results of the visual prosthesis after its implantation.
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