Restoring vision

Regenerating Vision

A UO team's implant that may restore vision loss caused by retinal diseases.

 

Most people say the worst sense to lose would be vision. However, one in four of us will face vision loss due to age-related macular degeneration by the time we hit 80.

But there is hope. An all-star team of UO experts representing five scientific fields is developing a novel implant that may one day restore sight lost to retinal diseases well enough to read, drive, and see color. This would truly be a breakthrough, because the implants available at present only restore the ability to perceive light in patchy gray monochrome.

It all began with physicist Richard Taylor wondering how to talk to a neuron. If you could convince neurons that they are interacting with other neurons rather than an artificial device, he reasoned, you could create a chip powerful enough to restore sight in people with diseased retinas. The idea emerged from his fascination with fractals, which are geometric patterns that mirror themselves at all levels of magnification. Nature favors fractals for everything from coral reefs and mighty oaks to the Milky Way. Even neurons.

Richard Taylor's dog, Griff, seen with normal 20/20 vision. Far right is also Griff at 20/1260, the limit of retinal implants using today's camera technology. For comparison, legal blindness is 20/200.

“Right now commercial electronics is based on Euclidean geometry, with wiring that follows along straight lines,” says Taylor, an expert in nanoelectronics and director of the UO’s Materials Science Institute. “This makes perfect sense in computers and cameras, but the body’s wiring doesn’t work that way. Our neurons, which act as the body’s wiring, are fractal. They have branches at many sizes, just like trees.”

Retinal implants are essentially electronic chips that restore sight by capturing light and converting it into an electrical signal, which is then passed down the neurons to the brain. The quest to realize Taylor’s vision of a fractal implant involves conquering a series of fundamental research challenges that the UO team is (or would be) the first to overcome. Their approach addresses crucial differences between how the human visual system and the camera “see.”

For an implant recipient, this would make the difference between navigating an open doorway and being able to read facial expressions. What’s more, today’s implants require special glasses and power sources. In contrast, fractal retinal implants would disappear into the eye itself and generate their own power from daylight. Best of all, they could restore the ability to see color.

In addition to Taylor, the retinal implant team is led by Assistant Professors Benjamín Alemán, BS ’04, (physics) and Cris Niell (biology) and Professors Miriam Deutsch (optics) and Darren Johnson (chemistry).

“A fundamental problem that we’re addressing is finding a way to talk to neurons that the body won’t reject,” says Alemán, an expert in carbon nanotubes whose doctorate, from the University of California at Berkeley, is in experimental quantum and nanoscale physics.

Neurons (dark blue) adhering to fractal interconnects.

From the outset, the team proposed using carbon nanotubes—crystalline metallic wires made up of pure carbon, with a diameter close to the width of a single strand of DNA—as the electrode interconnect with neurons because of their exceptional mechanical, electrical, and thermal properties. “The interconnects we are developing need to be metallic, to conduct electrical signals to the retinal neurons. They also need to be strong, to withstand the onslaught of forces encountered during an eye surgery and cell culturing. Most importantly, the cells must thrive on them,” Alemán says. “Carbon nanotube electrodes are the special sauce because they create a robust, intimate electrical connection while also supporting healthy growth of the neurons.”

Kara Zappitelli, one of four doctoral students involved in fabricating fractal electrodes and culturing neurons to grow on them, describes the process. “We make the chips by depositing a metal catalyst layer on silicon in the desired pattern,” she says. “Then we place them in a furnace and flow in carbon feedstock gases that cause a forest of carbon nanotubes to grow in the patterned regions. The top of our forest has a texture neurons seem to love.”


To produce the fractal retinal implant, the team must now hurdle at least three more major challenges. The first? “Showing that we can ‘talk’ to neurons growing on the chips, by pulsing the neurons with voltages applied to the nanotubes and measuring the neuron signaling,” Alemán says. Next, they must interface their retinal electrodes with existing technologies that convert light to electricity, which happens naturally in healthy eyes and is the key to “seeing.” Finally, they’ll shrink the implant down to the optimal size for Niell to place in the eyes of blind mice. If they can see, and more funding becomes available, the project could advance to human subjects.Student researchers incubate neurons with the electrodes. Within a week, the cells are growing on the nanotube forest as if attached by Velcro. “Our students have worked incredibly hard together to perfect the harvesting and culturing of neurons,” Alemán says. “They learned the technique from our collaborator Maria Thereza Perez of Lund University in Sweden. It would have been impossible without her.”

For an implant recipient, this would make the difference between navigating an open doorway and being able to read facial expressions. 

The stage was set for the implant project in 2015, when Taylor patented technology that covers any generic interface for connecting any electronics to a nerve. He shares the patent with Simon Brown, his research collaborator at New Zealand’s University of Canterbury, and their respective institutions. Soon after, Taylor bested more than 950 competing ideas to win an InnoCentive Prize. Next came two invitations to the White House and $1.8 million to cover startup costs from the W. M. Keck Foundation and the UO.

Taylor says this work builds on the UO’s 60-year tradition encouraging scientists in different fields to join forces. It also provides a glimpse of things to come from the UO’s new Phil and Penny Knight Campus for Accelerating Scientific Impact, whose mission is to make new treatments and technologies available as quickly as possible by applying a practical focus to insights gained from fundamental research.

Although the team’s current focus is human vision, Taylor says fractal technology is generic. If it repairs vision, it may also restore or enhance any number of things, from hearing to touch to targeting particular regions of the brain. “Long-term, a project like this is so exciting that you’ve got to be careful not to overexcite people,” he says, “but I really do think the sky’s the limit for this idea of interfacing artificial devices with living systems like the human body.”

Taylor, a trained painter and photographer famous for many discoveries involving fractal patterns, says it was probably inevitable that he’d end up looking at vision. But he emphasizes that he could never attempt this project alone.

“I’m always amazed at how if you keep your eyes open, you create your own luck,” he says, “and you get attracted to people who can help you.”

 

Melody Ward Leslie, BA ’79, is a UO staff writer.

 

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