In retinas with retinal degeneration, these microphotodiodes convert light energy contained in images into electrochemical impulses that stimulate the remaining retinal cells. The ASR microchip is self-contained, powered solely by incident light and does not require the use of external wires, batteries, headsets or ancillary computers. When surgically implanted under the retina—in a location known as “subretinal space”—the ASR chip is designed to produce visual signals similar to those produced by the photoreceptor layer. From their subretinal location, these artificial “photoelectric” signals from the ASR microchip can induce visual signals in the remaining functional retinal cells which may are then processed and sent via the optic nerve to the brain.
In initial laboratory testing, animal models implanted with ASR devices responded to light stimuli with retinal electrical signals (ERGs) and sometimes brain-wave signals (VEPs). The induction of these biological signals by the ASR chip indicated that visual stimulation had occurred.
Based on these studies, the FDA approved the conduct of clinical trials in collaboration with several university and VA medical centers that began in June 2000. These centers included the Hines, Cleveland and Atlanta Veterans Administration Medical Centers, Rush University Medical Center, Johns Hopkins Wilmer Eye Institute and Emory University Medical Center.