Professor JohnWyatt, of the London's University College Hospital's department of paediatrics and child health, said one of the issues was that the debate was extremely "polarised" with some seeing it as a black or white issue.
Normal vision is based on more than one hundred million receptors in each eye, but it is impossible to squeeze that many electrodes into a tiny device that has to lay on the retina, said JohnWyatt, a professor in the department of electrical engineering at MIT who has been working on a retinal prosthesis since 1988.