Stanford Researchers Plan to Replace Progressive Lenses With ‘Autofocals’

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When the call went out for volunteers to participate in a study on a new technology that could eventually improve on and replace progressive lenses, I was happy to sign up. Like every human over 50 years old, my eyes don’t accommodate as well as they used to. As we age, our eyes’ lenses stiffen, and we can either see near or far, but can’t adjust between them without the help of reading glasses, progressive lenses, or surgical monovision, depending on whether you are farsighted (Hyperopia) or nearsighted (Myopia).

Even if you have 20/20 vision at a distance, as you age you’ll need reading glasses to focus on a nearby book. None of the current solutions are great, and progressives are especially limiting since any given distance is only in focus in part of your field of view. When wearing mine, I’m often having to look up or down to focus on a particular object.

Restoring Your Eyes’ Ability to Autofocus

The current headset is quite a contraption but advances in AR wearables will allow for much more practical versions over timeResearchers working with Professor Gordon Wetzstein in the Computational Imaging lab at Stanford think they have an answer. Using a combination of eye tracking and an automatically adjusting external focus mechanism, whatever you look at through their Autofocals prototype is in focus. Essentially the device uses technology to mimic our eyes’ natural ability to focus at nearly any distance, which we lose with age. The current research prototype of Autofocals that project lead Nitish Padmanaban and fellow team member Robert Konrad used to test me is a large and somewhat unwieldy device. But if the concept proves out, it will only be a matter of time before it could become practical.

The tests involve an elaborate (and somewhat exhausting) series of eye chart reading exercises. I performed them with both my progressive lens glasses and using the team’s Autofocals device. One of the first things I noticed is that unlike with progressives, the Autofocals don’t require me to shift my gaze up and down to focus near and far. In the device’s current implementation, it has a tiny delay, but even in its prototype form it isn’t terrible.

Autofocals Build on Eye Tracking, Depth Camera

The Autofocals system relies on several components. An eye tracker lets the system know where you’re looking. Then a depth camera estimates the distance of whatever is in that direction. Finally, the liquid-filled lenses are electrically adjusted to focus at that distance. Since the system is pre-calibrated to the prescription of the person using it ahead of time, the refocusing provides a personalized optical correction optimized for the wearer and the distance.

For VR use, some of the same team are working on new display technologies that are focus invariant, to solve a similar issueWhat’s exciting to me about this approach is that eye tracking and depth cameras are both key elements of the future of vision wearables already, whether for AR or VR. So they will be improving in performance and decreasing in size and cost over the coming years. Similarly, there are a number of emerging technologies aiming to make adjustable focus lenses faster and higher quality. Once all these come together, Autofocals would be a logical extension.

Autofocals Outperform Monovision, Progressive Lenses

I don’t know what my personal results were, but the overall group of 24 of us (all aged from 51 to 81) had improved visual acuity, contrast sensitivity, and ability to match letters at near distances compared with either monovision or progressive lenses (the two types of subjects tested). That was achieved without sacrificing distance vision. In addition to making the current solution more practical, the team is interested in evolving it to become easier to calibrate, or perhaps self-calibrating.

The team will be presenting its work at SIGGRAPH in August, as well as allowing participants to try out the Autofocals prototype for themselves. This effort is only one of many aimed at using tech to improve vision, but it is certainly one of the most broadly applicable.

[Banner Image Credit: Stanistani/Wikimedia Commons]

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