Richard Williamson

Visual perception in a blind subject with a chronic microelectronic retinal prosthesis

A retinal prosthesis was permanently implanted in the eye of a completely blind test subject. This report details the results from the first 10 weeks of testing with the implant subject. The implanted device included an extraocular case to hold electronics, an intraocular electrode array (platinum disks, 4 x 4 arrangement) designed to interface with the retina, and a cable to connect the electronics case to the electrode array. The subject was able to see perceptions of light (spots) on all 16 electrodes of the array. In addition, the subject was able to use a camera to detect the presence or absence of ambient light, to detect motion, and to recognize simple shapes.

Visual task performance in blind humans with retinal prosthetic implants

A prototype electronic retinal prosthesis has been tested in three subjects. The system features an implanted retinal stimulator and an external system for image acquisition, processing, and telemetry. The subjects in general performed better than chance on psychophysical tests involving object detection, object counting, object discrimination, and direction of movement.

Electrical stimulation of retina in blind humans

A prototype electronic retinal prosthesis has been tested in two subjects. The system features an implanted retinal stimulator and an external system for image acquisition, processing, and telemetry. Subjects can perceive light when each of the 16 electrodes were activated. Stimulus thresholds ranged from 28 to 1417 /spl mu/A. Strength duration curves were obtained in all two subjects. Dynamic range for the brightness of the stimulus was demonstrated. Using the camera, the subjects were able to locate objects and determine the direction of movement.