Photo: Photo Courtesy of Retinal Implant AG
Before 2005, it was impossible to bring vision back to about 1.5 million people worldwide who suffer from an inherited form of blindness known as retinitis pigmentosa. “There was nothing else but the white cane, a guide dog or possibly speaking,” says Professor Eberhart Zrenner, the Founding Director of the Institute for Ophthalmic Research in Tubingen, Germany.
Today, Zrenner is the driving force behind a breakthrough implant technology that has enabled patients who had previously been blind for decades to recognise silverware on a table, read letters as words, and distinguish between different shades of grey.
The device, a three-by three-millimetre, 1,500 pixel electronic chip placed under the retina, is being developed by Retina Implant AG.
To date, 27 people have received the implant. Although still in clinical trial, the cutting-edge technology would radically transform the lives of those who have been robbed of sight.
Research and Development
Professor Eberhart Zrenner began researching retinal implants in 1995.
“Fifteen years ago, people thought this was a crazy idea,” said Zrenner. It wasn’t clear if the technology would work. New surgery procedures had to be developed and animal tests conducted before we switched to humans.
Photo: Photo courtesy of Retina Implant AG
The first human clinical trial was conducted in 2005. Eleven people received the eye implant for a temporary period. The results, published in the journal Proceedings of the Royal Society B in November 2010, were astounding.
After 17 years of living in darkness, a 45-year-old Finnish man was able to form letters into words, distinguish between a fork, a knife and a spoon, and recognise people from 20 feet away.
Zrenner describes other “at first sight moments”: patient 1 separates squares from triangles; patient 2 identifies spelling mistakes in his name MIIKKA , noting that one ‘I’ and one ‘K’ are missing; patient 3 correctly differentiates a large plate from a saucer.
In November 2011, the company got approval to extend the second human trial to two new locations in Germany as well as Oxford, London and Budapest.
In May 2012, as part of the second clinical trial, patients in the U.K. and Hong Kong were successfully fitted with the chip.
“I am able to make out a curve or a straight line close-up but I find things at distance more difficult,” British patient Chris James told BBC news after the implant was switched on for the first time.
The technology is not perfect. Zrenner admits this.
The chip has a resolution of 1,500 pixels (the typical human eye has a resolution of between 5 and 15 million pixels) and a 15 degree field of view. This means that someone within speaking distance of the patient would only appear as big as a passport photo.
Patients can also only see in shades of black of white. Zrenner compares the artificial vision to an old black-and-white TV screen where you have knobs with contrasts and brightness that can once again be adjusted.
The implant is typically switched on one week after surgery. Learning to reinterpret the black-and-white world takes about a month.
“Regaining vision means readjusting hand movement. In the beginning, they may see something in the brain, but for the hand to tell the brain exactly where to grasp takes time. Watching people discover their hand again—stretching the fingers and turning it around — that’s fascinating,” Zrenner said.
In March 2011, Retina Implant forged a partnership with the Wills Eye Institute in Philadelphia, which will serve as the main trial investigation site in the U.S., pending approval from the Food and Drug Administration.
The company may have marketing clearance in Europe as early as next year, according to Zrenner. There’s no price set yet, but he estimates that the unit would cost around $100,000.
Although the implant has only been tested on patients with retinitis pigmentosa so far, Zrenner is hopeful that technical advances and improvements in spatial resolution over the next few years will eventually allow his team to treat patients with age-related macular degeneration.
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