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Friday, January 18, 2008

Lights A Possible Platform For Superhuman Vision

Contact Lenses With Circuits, Lights A Possible Platform For Superhuman Vision

Movie characters from the Terminator to the Bionic Woman use bionic eyes to zoom in on far-off scenes, have useful facts pop into their field of view, or create virtual crosshairs. Off the screen, virtual displays have been proposed for more practical purposes -- visual aids to help vision-impaired people, holographic driving control panels and even as a way to surf the Web on the go.

The device to make this happen may be familiar. Engineers at the University of Washington have for the first time used manufacturing techniques at microscopic scales to combine a flexible, biologically safe contact lens with an imprinted electronic circuit and lights.

"Looking through a completed lens, you would see what the display is generating superimposed on the world outside," said Babak Parviz, a UW assistant professor of electrical engineering. "This is a very small step toward that goal, but I think it's extremely promising." The results were presented today at the Institute of Electrical and Electronics Engineers' international conference on Micro Electro Mechanical Systems by Harvey Ho, a former graduate student of Parviz's now working at Sandia National Laboratories in Livermore, Calif. Other co-authors are Ehsan Saeedi and Samuel Kim in the UW's electrical engineering department and Tueng Shen in the UW Medical Center's ophthalmology department.

There are many possible uses for virtual displays. Drivers or pilots could see a vehicle's speed projected onto the windshield. Video-game companies could use the contact lenses to completely immerse players in a virtual world without restricting their range of motion. And for communications, people on the go could surf the Internet on a midair virtual display screen that only they would be able to see.

"People may find all sorts of applications for it that we have not thought about. Our goal is to demonstrate the basic technology and make sure it works and that it's safe," said Parviz, who heads a multi-disciplinary UW group that is developing electronics for contact lenses.

The prototype device contains an electric circuit as well as red light-emitting diodes for a display, though it does not yet light up. The lenses were tested on rabbits for up to 20 minutes and the animals showed no adverse effects.

Ideally, installing or removing the bionic eye would be as easy as popping a contact lens in or out, and once installed the wearer would barely know the gadget was there, Parviz said.

Building the lenses was a challenge because materials that are safe for use in the body, such as the flexible organic materials used in contact lenses, are delicate. Manufacturing electrical circuits, however, involves inorganic materials, scorching temperatures and toxic chemicals. Researchers built the circuits from layers of metal only a few nanometers thick, about one thousandth the width of a human hair, and constructed light-emitting diodes one third of a millimeter across.

They then sprinkled the grayish powder of electrical components onto a sheet of flexible plastic. The shape of each tiny component dictates which piece it can attach to, a microfabrication technique known as self-assembly. Capillary forces -- the same type of forces that make water move up a plant's roots, and that cause the edge of a glass of water to curve upward -- pull the pieces into position.

The prototype contact lens does not correct the wearer's vision, but the technique could be used on a corrective lens, Parviz said. And all the gadgetry won't obstruct a person's view.

"There is a large area outside of the transparent part of the eye that we can use for placing instrumentation," Parviz said. Future improvements will add wireless communication to and from the lens. The researchers hope to power the whole system using a combination of radio-frequency power and solar cells placed on the lens, Parviz said.

A full-fledged display won't be available for a while, but a version that has a basic display with just a few pixels could be operational "fairly quickly," according to Parviz.

The research was funded by the National Science Foundation and a Technology Gap Innovation Fund from the University of Washington.

Technology Makes 'Super' Human Vision Possible
Adapting technology originally developed by astronomers to obtain better images of the heavens, a University of Rochester scientist has developed an optical system that has given research subjects an unprecedented quality of eyesight. The research dramatically improves the sight even of people who have 20/20 vision. Vision scientist David Williams presented his work this week at the summer meeting of the American Astronomical Society in Rochester, N.Y.

While the work is still in a research stage, eye-care giant Bausch & Lomb has licensed the technology and is working with University researchers to commercialize it.

"For years David has been way out in front exploring how we could enhance people's vision beyond what is normally thought of as perfect vision," says Scott MacRae, one of the world's leading cornea specialists and a widely recognized pioneer in refractive surgery. MacRae is moving to the University's Medical Center this month to join Williams at the newly established Alliance for Vision Excellence, a new collaboration between the University and Bausch & Lomb that is dedicated to improving technology to correct vision-impairing anomalies of the eye.

"In the old days," says MacRae, "we were just trying to correct people's vision problems and treat disease. This new research takes what we consider normal vision and enhances it. This is truly revolutionary," says MacRae, who is writing a book on such research, which he calls "the quest for super vision." Just last month at the annual meeting of the Association for Research in Vision and Ophthalmology, researchers from several laboratories and companies devoted a whole symposium to the topic of enhanced vision.

Williams uses technology known as adaptive optics, which was originally developed by astronomers to sharpen images from telescopes by correcting for aberrations in the atmosphere. Adaptive optics have been implemented on several telescopes, including the giant Keck Telescope in Hawaii, resulting in remarkably crisp images. Williams, who is Allyn Professor of Medical Optics and director of the University's Center for Visual Science, has led a decade-long effort to apply the technology to improve ordinary human vision.

His researchers direct a harmless, highly focused spot of light into the eye of a research subject and measure the light that is reflected outward. That light provides a glimpse or snapshot of the topography of the eye in exquisite detail. The light is broken up into 217 laser beams that are sent into a sophisticated device known as a wavefront sensor. The sensor analyzes deviations in each beam's path, revealing tiny imperfections or aberrations that exist in the person's cornea and lens.

The system detects visual distortions so subtle that physicians didn't even know they existed until Williams' laboratory invented the system. Today a visit to the eye doctor focuses mainly on two types of aberration: astigmatism and defocus. Most prescriptions are intended to correct for these two defects. Williams' system can measure up to 65 different aberrations.

These precise measurements are sent to a sensitive "deformable" mirror -- a mirror that can bend and customize its shape according to the measurements of a person's eye. Such flexible mirrors form the heart of traditional adaptive-optics systems used in astronomy. The mirror in Williams' laboratory is a two-inch-wide device that bends as little as one or two micrometers (just one-fiftieth the width of a human hair) thanks to 37 tiny computer-controlled pistons. This subtle shaping, done in response to the customized measurements of a person's optical system, alters the light in such a way that it exactly counters the specific distortions in a person's eye.

In the laboratory, Williams' team has shown that correcting these imperfections can result in greatly improved vision. He has published this work in the Journal of the Optical Society of America.

"When you look through an adaptive optics device, the world looks crisper," Williams says. "In some people, the ability to pick up contrast, such as minute patterns of stripes, is increased by a factor of six. It allows for a level of vision correction that's just not available today.

"It's like needing glasses and getting them for the first time. Everything suddenly looks sharper and clearer, no matter how good your eyes are normally. When you're using the adaptive optics system, you just say 'wow.' "

Williams is an expert on the circuitry of the human retina and the optics of the eye. After discovering some of the basic limits of the optical system of the human eye, he began exploring ways to improve ordinary human vision, eventually working closely with astronomers and other adaptive-optics experts. The research is now funded by the National Science Foundation Center for Adaptive Optics (based at the University of California, Santa Cruz), the National Eye Institute, and Bausch & Lomb.

Williams has found that the visual acuity of the human eye can be somewhere around 20/10. While adaptive optics may someday help patients approach that level, he says that acuity isn't the most noticeable improvement. Adaptive optics improves eyesight most under low-light conditions, such as night-time driving. MacRae, the laser surgery expert, estimates that a driver sharing the road with a bicyclist at dusk could see the bicyclist from roughly twice as far away if he or she were equipped with adaptive optics correction.

In the past, Williams has used the system to look into the eye. In a series of papers in such journals as Nature, Williams' team has published the best images ever obtained of the living human retina. Last year the team was able to differentiate the three types of cones in the living human retina. Detailed information of the eye is helpful to ophthalmologists monitoring patients with diseases like age-related macular degeneration or diabetic retinopathy.

While the current set-up is too bulky to bring the experience of enhanced vision or super vision to many patients, MacRae is confident that that day is not too far off.

"Someday you may no longer have to sit and answer patiently when you're asked repeatedly whether lens No. 1 or lens No. 2 is better," MacRae says. "Someday you may just look into a wavefront sensor as David has developed, and in one quick second we'll have all the information needed to improve someone's vision dramatically."

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