By Roland Piquepaille
We're all getting older, and many of us will suffer from some alteration of our sense of vision. We might be one day affected by age-related macular degeneration (AMD), which causes blindness to 700,000 people in the Western world every year. But now, ophthalmologists and physicists at Stanford University have teamed up to design a 'bionic eye'. This system works like some 'virtual reality' devices. A little video camera is mounted on transparent goggles allowing for simultaneous use of remaining natural vision. Images from the camera are processed by a microcomputer and projected on the retina. The 'bionic eye' which also includes a solar-powered battery implanted in the iris, is currently tested with rats, but human testing could start within three years. Read more...Here is an excerpt from the introduction of this news release.
[These researchers have designed] an optoelectronic retinal prosthesis system that can stimulate the retina with resolution corresponding to a visual acuity of 20/80 -- sharp enough to orient yourself toward objects, recognize faces, read large fonts, watch TV and, perhaps most important, lead an independent life. The researchers hope their device may someday bring artificial vision to those blind due to retinal degeneration.
And here is a description of the problem.
Worldwide, 1.5 million people suffer from retinitis pigmentosa (RP), the leading cause of inherited blindness. In the Western world, age-related macular degeneration (AMD) is the major cause of vision loss in people over age 65, and the issue is becoming more critical as the population ages. Each year, 700,000 people are diagnosed with AMD, with 10 percent becoming legally blind, defined by 20/400 vision. Many AMD patients retain some degree of peripheral vision.
As there is no effective treatment for most patients with AMD and RP, the researchers tried to directly stimulate the inner retina with visual signals.
To that end, the researchers plan to directly stimulate the layer underneath the dead photoreceptors using a system that looks like a cousin of the high-tech visor blind engineer Lt. Geordi La Forge wore in Star Trek: The Next Generation. It consists of a tiny video camera mounted on transparent "virtual reality" style goggles. There's also a wallet-sized computer processor, a solar-powered battery implanted in the iris and a light-sensing chip implanted in the retina.
The system has been designed by Daniel Palanker and his colleagues of the Group of BioMedical Physics and Ophthalmic Technologies. Here is how it works.
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"The image from a goggles-mounted video camera is processed in a portable microcomputer and then projected with a pulsed IR LED-LCD array onto the retina." (Credit: Daniel Palanker) This image comes from this page about artificial vision and optoelectronic retinal prosthesis. |
The chip is the size of half a rice grain -- 3 millimeters -- and allows users to perceive 10 degrees of visual field at a time. It's a flat rectangle of plastic (eventually a silicon version will be developed) with one corner snipped off to create asymmetry so surgeons can orient it properly during implantation.
The research work has been published by the Journal of Neural Engineering on February 22, 2005 (Volume 2, Number 1, March 2005) under the name "Design of a high-resolution optoelectronic retinal prosthesis." Here is the end of the abstract, which summarizes how the system works.
To provide for natural eye scanning of the scene, rather than scanning with a head-mounted camera, the system operates similar to 'virtual reality' devices. An image from a video camera is projected by a goggle-mounted collimated infrared LED-LCD display onto the retina, activating an array of powered photodiodes in the retinal implant. The goggles are transparent to visible light, thus allowing for the simultaneous use of remaining natural vision along with prosthetic stimulation. Optical delivery of visual information to the implant allows for real-time image processing adjustable to retinal architecture, as well as flexible control of image processing algorithms and stimulation parameters.
And if you need more information, please read the whole well-written news release.
Sources: Dawn Levy, Stanford University News Service, March 30, 2005; and various websites
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