Another RPB research team is developing a retinal prosthetic device called the Intelligent Retina Implant System (IRIS). While similar to other experimental visual prostheses, the IRIS will use 3,200 electrodes to create much higher resolution images. It also will be capable of compensating for changes in retinal structure resulting from retinal degeneration. This will allow the patient to make adjustments that optimize the visual image after implantation surgery.
Other RPB artificial retina projects include: a Thumbtack Photovoltaic Retinal Prosthesis that will incorporate self-powered, light-to-current transducers within the eye, with all interface circuitry outside the eye; and a retinal prosthesis that relies on a biochemical agent for neurotransmission, which may more closely mimic natural visual stimulation than prostheses using electrical stimulation.
The system took more than 15 years to develop and test, with support from RPB and other government and private sources. It uses a video camera attached to a pair of eyeglasses to capture images. The images are sent to a video processing unit that wirelessly transmits data to an implanted retinal prosthesis. The prosthesis, containing 60 electrodes, sends signals to the brain.
As a patient's brain learns to interpret the transmitted patterns of light and dark, he or she may start to identify the location and movement of objects. To be eligible for the device, patients will have to have inner layer retina function and a history of being able to see forms, and they will be required to have clinical follow-up and visual rehabilitation, according to the FDA, which recently approved the Argus II.