There are also many technical challenges, such as how to add more electrodes into the tiny chip that sits on the retina—about 5 millimeters by 7 millimeters in the case of Argus II—to stimulate enough cells in the retina to produce a good quality image. Normal vision is based on more than one hundred million receptors in each eye that process light, say experts.
Many other academic centers and companies are working on competing technology they say is more advanced than Second Sight's.