An estimated 170 million people worldwide suffer from age-related macular degeneration (AMD), a serious eye condition marked by the death of light-sensitive cells in the retina. Doctors can slow macular degeneration with vitamins, laser surgery, stem cell treatments, and even implantable miniature telescopes. But many sufferers ultimately go blind.
In 2013, the FDA approved an artificial retina that could help restore limited vision to people with degenerative eye diseases. But the device relied on a sunglass-mounted external camera and a transmitter that relayed sight information to the retinal implant.
Now researchers at the Italian Institute of Technology in Genoa and the University of California, San Diego have crafted artificial retinas that can be implanted entirely inside the eye, which offer hope to those with macular degeneration.
The devices are only experimental prototypes with many years of additional research and development likely before they might be ready for commercial use. But Dr. Grazia Pertile, director of ophthalmology at the Sacred Heart Don Calabria in Negrar, Italy and one of the Italian researchers, said in a written statement that her team's device could be "a turning point in the treatment of extremely debilitating retinal diseases."
She's not alone in that assessment.
"This is definitely a game changer," Dr. Kapil Bharti, an investigator at the National Eye Institute in Bethesda, Maryland who is not involved with the research, says. "Previous versions of these work in a very, very low-resolution range. Patients were practically still blind and incapacitated as far as everyday tasks were concerned. These promise that patients could become more independent."
When healthy, retinal cells transmit visual information to the brain. As these cells die off, AMD sufferers lose their central vision. The new prosthesis is designed to be implanted onto the back wall of the eye, where it absorbs light and transforms it into an electrical signal that stimulates the still-active retinal cells to restore vision.
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When the prosthesis was tested in rats, the animals' pupils constricted in response to exposure to light. The researchers were unable to determine how well the rats were able to see, if at all, but they noted that the animals' eyes continued to react to light more than six months after the implant was installed.
"We hope to replicate in humans the excellent results obtained in animal models," Pertile said. The team will conduct human trials later this year.
The findings were published in the journal Nature Materials.
The researchers in San Diego have taken a different approach to solving AMD that they think can restore vision to resolutions as sharp as a healthy eye.
There, engineers have partnered with Nanovision Biosciences Inc. to create a retinal implant that uses silicon nanowires smaller than the width of a cell to sense light entering the eye and stimulate retinal neurons. Powered by a small wireless device, this circular array of nanowires mimics densely packed retinal cells to help achieve "functional vision," says Gabriel A. Silva, professor of bioengineering and ophthalmology at UC San Diego.
"We want to create a new class of devices with drastically improved capabilities to help people with impaired vision," Silva said.
The findings were reported in the Journal of Neural Engineering.
Neither of the implants is able to restore color to vision yet, and Bharti has questions about the durability of organic eye implants. But, he says, "Those are things that can be easily worked out and can be done in the coming future. Overall, this is very exciting."