In the U.S., more than 40 percent of 40-year-olds need eyeglasses for reading, and that figure jumps to nearly 70 percent for people aged 80 and older. “As we get older, refractive errors play more significant roles in our lives,” says Gordon Wetzstein, an assistant professor of electrical engineering at Stanford University.
But glasses and contact lenses are not always ideal. If you are farsighted, for example, you do not need glasses to see traffic while driving, but you do need them to read your speedometer or GPS. The best solution in such cases, Wetzstein says, would be vision-correcting displays—screens that wear the glasses for you.
Wetzstein and his colleagues at M.I.T. (where he was formerly based) and the University of California, Berkeley, have developed just such a screen. The vision-correcting display makes two modifications to a standard high-resolution smartphone or tablet screen. The first is a low-cost, pinhole-covered printed transparency that covers the screen. The second: algorithms coded into the smartphone or tablet that determine the viewer's position relative to the screen and distort the image that is projected, according to his or her prescription. As the distorted image passes through the matrix of pinholes in the transparent screen cover, the hardware-software combination creates errors on the screen that cancel errors in the eye, thus delivering what appears to be a crisp image. The screen can correct for myopia, hyperopia, astigmatism and more complicated vision problems. The team presented the work at the SIGGRAPH conference in August in Vancouver.
Informal tests on a handful of users have shown that the technology works, Wetzstein says, but large-scale studies are needed to further refine it. In the process, the researchers also plan on developing a slider that can be used to manually adjust the focus of the screen. Wetzstein says that the technology could be a boon for people in developing countries who have easier access to mobile devices than prescription eyewear.
Editor’s note: The four authors of the SIGGRAPH paper were Fu-Chung Huang of the Computer Science Division at the University of California, Berkeley, and Microsoft; Gordon Wetzstein of the M.I.T. Media Lab; Brian A. Barsky of the Computer Science Division and School of Optometry at University of California, Berkeley; and Ramesh Raskar of the M.I.T. Media Lab.