While several companies and laboratories around the world are at various stages of bionic-retina development, Pixium Vision located in France, is progressing impressively down two paths for these high-tech, vision-restoring systems. Both approaches show strong, near-term potential for providing meaningful vision to people who are otherwise blind from retinal diseases such as retinitis pigmentosa and age-related macular degeneration (AMD).
Pixium recently announced that its IRIS®II bionic vision system received a CE Mark, the regulatory approval necessary for marketing medical devices and other products in Europe. The IRIS II is further down the company’s clinical development pipeline than its more technologically advanced PRIMA system, which was originally conceptualized by researchers at Stanford University, and is expected to enter a clinical trial later this year for AMD.
The basic IRIS II design is similar to that of the Argus II, the retinal prosthesis developed by Second Sight, and first to become commercially available — since 2013 in the United States and 2011 in Europe. Both the Argus II and IRIS II use a camera embedded in glasses to deliver visual information to an electronic chip that’s implanted adjacent to the user’s retina. Working as a rudimentary replacement for lost photoreceptors, the retinal cells that make vision possible, the “epi-retinal” chip transmits signals back to the brain, where they are interpreted as vision.
However, Khalid Ishaque, Pixium’s chief executive officer, says that the IRIS II has three distinct advantages over the Argus II. First, the IRIS II chip has 150 electrodes (i.e., pixels) versus 60 for the Argus II. That could translate to higher resolution vision for users. Second, the IRIS II camera transmits only changes in the patient’s visual field, making it more efficient and faster than the Argus II camera, which captures everything in the user’s visual field, requiring more work for the system’s image processor to parse visual input. Last, unlike the Argus II, the IRIS II chip is designed to be easily replaced with upgraded models.
With that said, the Argus II has a more established clinical track record, having been implanted in well over 100 patients in the U.S. and Europe. Also, full results from the 10-patient IRIS II clinical trial in Europe have not yet been reported. Pixium plans to launch a clinical trial of its system in the U.S. soon — within the next year. Both the Argus II and IRIS II are designed to improve the mobility and independence of people who are completely blind from retinal diseases by enabling them to recognize large objects, shapes, and movement.
Second Sight has a next-generation device, the Orion I, in development. It will use Argus II technology, but will bypass the user’s eyes and optic nerves — circumventing virtually all ocular conditions and diseases — and connect directly to the visual cortex, the part of the brain responsible for vision. Second Sight plans to begin a clinical trial of the Orion I in 2017.
In the near-term, the most vision restoration may come from Pixium’s PRIMA, a significantly more advanced bionic retinal system. The PRIMA involves the implantation of one or several tiny photovoltaic (light-sensitive) diodes underneath the retina. Collectively, the modular diodes are designed to provide as much as 5,000 pixels of vision, and form better connections with the patient’s existing retinal tissue than epi-retinal chips. Ishaque says the implantation process is like paving the back of the retina with tiny solar panels. The PRIMA should provide signaling that is more like the natural signals emanating from photoreceptors. Users of the PRIMA will wear glasses that transmit near-infrared light to deliver visual information and power to the diodes.
Ishaque is cautiously optimistic about the PRIMA’s potential to provide more useful vision for daily living tasks than other available bionic retina technologies, acknowledging that it has yet to be evaluated in humans. In the meantime, the IRIS II provides Pixium with a vision-restoring alternative that’s available today to patients in Europe, enabling them to live more independent lives.