An effective treatment for Macular degeneration (AMD), which causes blindness in millions of people in the Western world, could be on the cards in the future.
A new study done by researchers from
Bar-Ilan University and Stanford University found, for the first time, evidence indicating that the brain knows how to integrate natural and artificial vision, while maintaining processing information that is important for vision.
Prof. Yossi Mandel, head of Bar-Ilan University’s Ophthalmic
Science and Engineering Lab and the study’s lead author, explained to The Jerusalem Post that AMD stands for Age-related Macular Degeneration, which “is caused by ageing changes of the light receptors (photoreceptor layer and an adjacent supporting layer called retinal pigment epithelium.
“Continuous exposure of these layers to light, heat and oxidative stress cause chronic damage which eventually can lead to photoreceptors loss and blindness,” he said. “AMD is the leading cause of blindness 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.
Inside the eye’s retina are light receptors or photoreceptors, which absorb light, a press statement said.
“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,” it continued. “ 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.
The researchers explained that 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,” they said in the statement. “AMD patients implanted with an artificial retina possess a combination of artificial central vision and normal peripheral vision.”
Mandel highlighted that it is important to study the combination of artificial and natural vision “in order to understand how to help the blind.
“One of the critical questions in this regard is whether the brain can integrate artificial and natural vision properly,” he addded.
Mandel told the Post that the research was conducted in his lab during a process of about two years and was mainly carried by Tamar Arens-Arad as part of her doctoral studies.
“This is part of a long collaboration with Prof. Daniel Palanker of Stanford University, who developed the retinal prosthetic device,” he said. “The device is composed of tenth of tiny solar cells, each is connected to an electrode” and the device is implanted below the retina of rodents.
“We have developed a unique projection system that can project invisible light or visible light (green light) to stimulate either the prosthetic device or the normal adjacent retina, respectively, while recording the activity of the visual cortex, which is the area in the brain responsible for processing the information arriving from the retina,” he continued. “Using this model enables us to study the interactions between prosthetic (artificial) and natural vision.”
According Arens-Arad, the researchers “used a unique projection system which stimulated either natural vision, artificial vision or a combination of natural and artificial vision, while simultaneously recording the cortical responses in rodents implanted with a subretinal implant.
“The implant is composed of dozens of tiny solar cells and electrodes, developed by Prof. Daniel Palanker at Stanford University,” Arens-Arad added.
For Mandel, “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,” he highlighted.
Asked about when this could be available to patients, he said “the treatment is under evaluation in humans.
Mandel said that the animal studies enables us to study basic questions, which can not be performed in humans. “For example, it is very difficult to non-invasively record brain activity in humans at high resolution.
“These studies can aid in deepening our understanding on prosthetic vision and improving the vision restoration in humans,” he emphasized. “We are now carrying more research to study brain activity using optical recording which enable high resolution recording during prosthetic activation.”
The study was published in the journal Current Biology.