Stanford Team Develops Autofocals with Eye-Tracking Sensor Technology

Presbyopia is one of life’s guarantees like death and taxes. This vision defect begins to plague people nearing the age of 45, as the lenses in the eyes lose the elasticity required to focus on objects that are close at hand. For certain people reading glasses are enough to overcome the struggle, but for many people the only solution, short of surgery, is to switch to progressive lenses.

Stanford engineers are testing a pair of smart glasses that can automatically focus on whatever you’re looking at. (Image credit: Robert Konrad)

“More than a billion people have presbyopia and we’ve created a pair of autofocal lenses that might one day correct their vision far more effectively than traditional glasses,” said Stanford electrical engineer Gordon Wetzstein. At present, the prototype resembles virtual reality goggles but the team hopes to modernize later versions.

Wetzstein’s prototype glasses – labeled autofocals – are meant to solve the main issue with present-day progressive lenses: These traditional glasses need the wearer to align their head to focus accurately. Visualize driving a car and looking in a side mirror to switch lanes. With progressive lenses, there is limited or no peripheral focus. The driver has to switch from looking at the road ahead via the top of the glasses, then turn nearly 90° to see the immediate mirror via the lower part of the lens.

This visual move can also make it hard to navigate the world. “People wearing progressive lenses have a higher risk of falling and injuring themselves,” said graduate student Robert Konrad, a co-author on a paper explaining the autofocal glasses published in the June 28th issue of the journal Science Advances.

The Stanford prototype functions quite like the lens of the eye, with fluid-filled lenses that bulge and thin as the field of vision varies. It also comprises eye-tracking sensors that triangulate where a person is looking and establish the precise distance to the object of interest. The researchers did not invent these lenses or eye-trackers, but they did create the software system that harnesses this eye-tracking data to maintain the fluid-filled lenses in constant and seamless focus.

Nitish Padmanaban, a graduate student and the first author of the paper, said other teams had earlier attempted to apply autofocus lenses to presbyopia. But without direction from the eye-tracking hardware and system software, those previous efforts merely amounted to being the same as wearing traditional progressive lenses.

To corroborate its method, the Stanford team tested the prototype on 56 people with presbyopia. Test subjects stated the autofocus lenses worked better and faster at reading and other activities. Wearers were also inclined to favor the autofocal glasses to the experience of progressive lenses – weight and bulk aside.

If the method sounds a little like virtual reality and that is not far off. Wetzstein’s lab is at the vanguard of vision systems for augmented and virtual reality. It was during such work that the team became mindful of the new autofocus lenses and eye-trackers and had gained the understanding to join these elements to develop a potentially transformative product.

The following step will be to miniaturize the technology. Wetzstein states that it may take some years to create autofocal glasses that are energy efficient, lightweight, and stylish. But he strongly believes that autofocals are the future of vision correction.

This technology could affect billions of people’s lives in a meaningful way that most techno-gadgets never will.

Gordon Wetzstein, Electrical Engineer, Stanford University

Gordon Wetzstein is also director of the Stanford Computational Imaging Lab and a member of Stanford Bio-X and the Wu Tsai Neurosciences Institute.

This study was sponsored partly by Intel Corporation, NVIDIA, an Okawa Research Grant, a Sloan Fellowship and the National Science Foundation.

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