Current status of artificial vision by electrocortical stimulation.

The history of the provision of artificial vision by electrocortical stimulation has its origin in observations over 50 years ago. However, the realistic modern stimulation of human visual cortex is only 20-years-old. No useful device has been devised as yet and it therefore remains purely experimental. The primary objective of such a prosthetic device is that of independent mobility. This would require the appreciation of half-tone pictures, the detection of depth and discontinuities in outlines, and a significant quality of resolution. Some of the problems which threaten resolution in such a device and the factors which must be overcome in order to achieve a useful visual prosthesis are discussed.