The Argus II retinal implant is like a
cochlear implant for the
blind. It looks like
computing goggles such as Google Glass, but it sends the images the eyeglass-mounted visual processing unit detects to a tiny electrode array that's been implanted in the user's retina. Electrical stimulation sends visual information up the optic nerve to the visual cortex of the user's brain, allowing him or her to see.
In a recent
study on eight people with end-stage RP, those using the implant were twice as likely to be able to correctly identify photos of objects with their outlines enhanced as those who received a scrambled signal from the implant. Without the assistance of the enhanced outlines, patients using the implants successfully identified objects in photos 25 percent more often than those in the positive control group.
The Argus II was
approved in the United States as a humanitarian device, a status that certifies it as safe and likely to help. While standard approval would have required clinical trials on 300 patients, that status required just 30 test subjects. With an outlay of $1 million per patient, the more limited trials were the only viable decision, Brian Mech, Second Sight's vice president for business development, told Singularity Hub.
Second Sight and its government partners are working toward a device that would allow patients to see well enough to recognize faces — and, potentially, as the technology improves,
better even than people with 20/20 vision. Increased accuracy requires more electrodes in the implant, and the challenge is in keeping it tiny.
The Argus II implant includes 60 electrodes, but the planned
Argus III will
likely include 240. The more powerful implant won't be approved and available to patients for several years, according to Mech.
Second Sight can continue to improve the sight of patients using the Argus II device by ramping up the visual processing unit and
fine-tuning the software that feeds the implant, he said. Backers also hope the retinal implant will be okayed for use in patients with macular degeneration, the leading cause of blindness in those aged 60 and over.
Patients, such as those suffering from glaucoma, which damages the ocular nerve, wouldn't benefit from the implant. But Second Sight is developing an implant that stimulates the brain itself rather than relying on the ocular nerve to send the signal.
Such a device faces a far more daunting risk-benefit calculus. If in early testing the current implants had further damaged patients' eyes, for instance, it wouldn't have mattered much since they were already legally blind. (Few people are completely blind, but patients' quality of life wouldn't have been seriously affected.) Damage to a blind patient's brain, on the other hand, would be a catastrophic clinical outcome.
"We could address all forms of blindness. From a technical perspective, we have what we need; it's just the clinical risk that we have to figure out," said Mech.
Devices that attach directly to the brain and provide computer-enhanced vision sound like a page torn from a future playbook, to be sure. But here in the present, even the more modest Argus II bionic implant has stirred enough interest to be named by several publications, including Time, CNN and Scientific American, as one of the most important inventions of 2013.
Mohan K. Ponnath
No comments:
Post a Comment