Research by Israeli and US scientists suggests that the brains of blind people who get artificial retina implants may be able to process information from the implant and integrate it successfully with stimuli coming naturally from other parts of the retina.
The finding could pave the way to better restore vision in patients who suffer from one of the most common causes of blindness, the researchers said.
In the study, published in the journal Current Biology, researchers from Israel’s Bar-Ilan University and Stanford University in the US show “for the first time” evidence indicating that the brain knows how to integrate natural and artificial vision, while maintaining and processing information that is important for vision, according to a statement by the universities.
Macular degeneration (AMD) causes blindness in millions of people in the Western world. It is the most common cause of severe vision loss in the Western world among those aged 50 and over, and its prevalence increases with age. Though there is no cure for AMD, significant recent advancements in artificial retina implants may lead to effective treatment.
Located inside the eye, the retina contains light receptors (photoreceptors) that absorb light. Information is then processed and transmitted to the brain. The macula, the central area of the retina, processes most of the information that reaches the brain from the eye, enabling one to see while reading and driving, facial recognition, and any other activity that requires accurate vision.
In the peripheral retina, the area of the retina outside the macula that assists mainly with spatial judgment, vision is 10-20 times less precise. In AMD precise vision is impaired due to damage to the center of the retina, while peripheral vision remains normal.
When there is damage to the photoreceptor layers in the retina, an artificial retina — a device built from tiny electrodes smaller in width than a hair — may be implanted. Activating these electrodes results in electrical stimulation of the remaining retinal cells and results in visual restoration, albeit partially.
AMD patients implanted with an artificial retina possess a combination of artificial central vision and normal peripheral vision.
The researchers studied how this combination of artificial and natural vision is processed by the brain, and whether the brain can integrate artificial and natural vision properly, so as to know how further to develop products that can help people with blindness.
“We wanted to see how the brain is able to combine the two kinds of information, because it can provide us insight which is important for improving the restoration of sight in blind patients,” said Prof. Yossi Mandel, head of Bar-Ilan University’s Ophthalmic Science and Engineering Lab and the study’s lead author. The study has also “potentially other applications, because, in a way it is a sort of a human-machine interaction,” with the machine part being the artificial retina.
“The visual cortex in our brain processes the information from the retina, and we wanted to find out if the brain was able to process and analyze and integrate the information coming both from the prosthetic retina and natural retina,” he said. “This will enable the implanted person to see, even if part of the information was coming from an artificial chip.”
In their work the researchers implanted rodents with implants similar to those created for humans and studied the activity of the brain. The implant — the prosthetic retina — is composed of dozens of tiny solar cells and electrodes, and was developed by Prof. Daniel Palanker at Stanford University.
“What we found is that the basic processing (abilities) of the visual cortex are preserved, and it is able to combine the artificial and natural signals, just as it does when both signals come naturally, when people have natural eyesight,” he said.
“These pioneering results have implications for better restoration of sight in AMD patients implanted with retinal prosthetic devices and support our hypothesis that prosthetic and natural vision can be integrated in the brain. The results could also have implications for future brain-machine interface applications where artificial and natural processes co-exist,” Mandel added.
The research was carried out in Prof. Mandel’s lab at the School of Optometry and Vision Science, Mina and Everard Goodman Faculty of Life Sciences and the Institute of Nanotechnology and Advanced Materials (BINA) at Bar-Ilan University’s, in collaboration with Prof. Palanker of Stanford.