Abstract
Purpose: :
To develop a sensory substitution device in which corneal stimuli are used to generate neural input to the brains of visually compromised people to substitute for absent retinal input.
Methods: :
The device will composed of spectacles-mounted cameras wirelessly transmitting processed images to a special contact lens translating the visual information into tactile stimulation of the corneal nerves. A low energy electric stimulation of the corneal nerves is investigated as well. In order to improve the spatial resolution of the constructed image, the camera will also time multiplex, compress and encode the captured image before transmitting it to the stimulating contact lens.
Results: :
Preliminary devices based upon tactile stimulation of the edge of fingers by applying mechanical pressure and of the tongue by applying proper electrical stimulation, were constructed and tested. The mechanical stimulator included ADUC841 micro-processor whose outputs after being amplified was connected to 25 solenoids who applied the mechanical pressure. 5 subjects were taught to "see" and to recognize simple patterns using this mechanical stimulation device. The electrical tactile sensory included USB camera as image acquisition device, the image signals were transmitted via NI USB Digital I/O card and then amplified using TI RC4136 OP-AMP circuit. The output was connected to a tongue stimulation device which was a specially designed 4 layers PCB with 100 stimulation points.Prototype of the desired cornea/sclera stimulating contact lens is currently being constructed.
Conclusions: :
We propose novel concept of solving some of the vision problems of blind people via non-retinal mechanical and/or electrical stimulation of the cornea. Vision substitution obtained by mechanical stimulation of the finger tips and by electrical stimulation of the tongue was demonstrated.
Keywords: innervation: sensation • scene perception