Stimulation of human visual cortex is known to elicit visual perceptions that could potentially be used for restoring artificial vision to individuals who have lost their vision due to non-cortical etiologies. Although there have been attempts to build brain stimulators for the visual cortex in the past, fully implanted, chronic cortical visual prostheses have remained theoretical until recently. The Orion Visual Cortical Prosthesis System, which is currently being tested in a clinical trial, is a new device that is intended to restore some functional vision to blind patients.
This is a five-year, prospective, non-randomized, single-arm early feasibility study (clinicaltrials.gov NCT03344848) of subjects who are bilaterally blind with bare light or no light perception due to non-cortical etiology. The main objectives are to evaluate the safety of placing and activating an electrode array on the medial surface of the occipital lobe in blind patients; to evaluate the functionality of the device; to perform research to study the nature of the vision provided by the Orion; and to obtain input for future device design. There are five subjects between two study centers.
The Orion System comprises an implant (consisting of an electronics package, receiving antenna, and an electrode array with 60 non-penetrating electrodes); glasses with a video camera; headwear containing a transmitting antenna; and a video processing unit (VPU). The video camera collects real-time visual information, which is then processed by the VPU and converted to stimulation patterns on the electrode array. A radio frequency link between the transmitting and receiving antenna sends data and power to the implant.
Four subjects have been implanted at UCLA, three males and one female. As of January 30, 2019, average implant duration was 9.8 months. Average age at time of implant was 50.3 years. Cause of blindness included trauma (burn), trauma (car accident), infection, and pediatric glaucoma. All subjects had bare or no light perception at the time of implant, but were previously sighted.
All subjects reports seeing phosphenes with stimulation through virtually all electrodes implanted. Stimulation parameters are within expected ranges and generally stable over time. Despite similar implant techniques, spatial maps vary by subject but are generally stable within subjects. The field of view is larger than that seen with retinal prosthetics. Early testing with light localization and direction of motion testing reveal the ability to detect motion in most subjects. Real world use has shown the ability to use the device to navigate the environment. One serious adverse event of seizure has been noted. Future work will focus on maximizing stimulation parameters and working with visual rehabilitation specialists to maximize utility.