Artificial Photoreceptors Could Save Sight for Millions
Remember Geordi La Forge from Star Trek: The Next Generation? Sightless from birth, yet able to see an electromagnetic world, hidden from the rest of us, through a futuristic bionic visor. It’s all science fiction, of course, but throughout its history, science fiction has had a persistent way of transforming into science into reality. So Geordi’s device begs the question: are we anywhere close to developing bionic devices for impaired vision, given our current technology?
The short answer is yes, and in fact, we’re much closer than you might think. According to researchers at NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust, London, UK, “…Retinal prosthesis systems have undergone significant advances in the past quarter century… To date, four systems have received marketing approval for use in Europe or the United States, with numerous others undergoing preclinical and clinical evaluation.”[i]
These devices treat conditions like retinitis pigmentosa and macular degeneration, which destroy photoreceptor cells – special cells, crucial to vision, that work in concert with a chain of inner neurons to turn light into signals the brain can interpret. Fortunately, these diseases generally leave the inner neurons unharmed. Bionic eyes, also known as artificial retinal implants, replace damaged photoreceptors and electrically stimulate surviving, healthy inner neurons.
Currently, only one of those systems is commercially available in the US: the Argus II Retinal Prosthesis System, made by Second Sight Medical Products, Inc., and it doesn’t offer Geordi La Forge’s electromagnetic eyesight. It does, however, include vidor-like glasses, which attach to a processor and mini video camera. The result is partial vision restoration – not good-as-new, but users regain enough sight to navigate around large objects.
That’s an immense improvement for most patients, and even greater ones are on the way. Scientists in China recently went a step further and restored full-color vision in mice with artificial photoreceptors, made out of imperceptibly small nanowires and using no processors or external power source. In the UK, investigators have successfully used regenerative medicine, that is, stem cell implants, to substantially improve vision in patients with age-related macular degeneration (AMD).
Right now, retinal implants can allow previously blind patients to detect light, locate objects, and determine object motion direction. But so far, they haven’t been able to bring visual acuity (VA) above the legal blindness level (VA <20/200).
Now, even that may be about to change. A team at Shri Jagadish Prasad Jhabarmal Technical University (JJTU) have developed a photovoltaic array for a sub-retinal implant, which can improve VA to 20/180. By contrast, the ARGUS II improves VA only to 20/1262. This could prove a major advance in the fight against blindness.