The dream of curing blindness started in the early sixties in England with Dr. Giles Brindley’s research and culminated in 1968 when he implanted in a blind volunteer an electrode array of 80 stimulating electrodes against the visual cortex of the right hemisphere of her brain. He demonstrated that it was possible to transfer external visual information into the patient’s mind, such that she could identify simple patterns and letters from combinations of multiple phosphenes. Inspired by Brindley’s work, Dr. William Dobelle devoted himself to the research of artificial vision with the aim of making a visual prosthesis that could eventually restore vision to the blind.
The project is the continuation of Dr. DoBelle’s work. Evaluation of vision prosthesis is essential to understand its performance in implanted patients. However it also carries great risk to the subject as the stimulations are directly applied to the visual nerve system. It is unsafe to expose the patient under long term stimulation. Vision prosthesis simulator can achieve the same goal but avoid risks associated with the real implanted prosthesis.
The simulator includes a web camera, a laptop PC and a head mounted display (HMD). The web camera captures the image and sends. it to the laptop for processing. The laptop converts the image into phosphene dots and display them in the HMD. Since the HMD can serve as a blindfold, the subject can only view the phosphenes in the HMD. Therefore, sighted subjects can use the simulator and have the same experience as the implanted blind patients. The simulator is a valuable tool for the study of the efficacy and psychological effects of the implanted vision prosthesis. The simulator software was written in LabVIEW.
The web camera captured the object image with high contract edges. The image was processed and the edges were extract. Those edge lines were overlapped with the phosphene maps from the patient and the phosphenes on or close to the edge were selected. The phosphene maps were from one of the DoBelle’s patients. The electrodes corresponding to those phosphenes were stimulated so that phosphenes in the blind patient’s visual field formed an “image” related to the object.