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Autofocusing reading glasses of the future

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    Every single one of us will lose
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    or has already lost something
    we rely on every single day.
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    I am of course talking about our keys.
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    (Laughter)
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    Just kidding.
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    What I actually want to talk about is one
    of our most important senses: vision.
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    Every single day we each lose
    a little bit of our ability
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    to refocus our eyes
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    until we can't refocus at all.
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    We call this condition presbyopia,
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    and it affects two billion
    people worldwide.
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    That's right, I said billion.
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    If you haven't heard of presbyopia,
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    and you're wondering,
    "Where are these two billion people?"
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    here's a hint before
    I get into the details.
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    It's the reason why people wear
    reading glasses or bifocal lenses.
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    I'll get started by describing
    the loss in refocusing ability
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    leading up to presbyopia.
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    As a newborn, you would have
    been able to focus
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    as close as six and a half centimeters,
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    if you wished to.
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    By your mid-20s, you have about
    half of that focusing power left.
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    10 centimeters or so,
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    but close enough that you never
    notice the difference.
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    By your late 40s though,
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    the closest you can focus
    is about 25 centimeters,
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    maybe even farther.
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    Losses in focusing ability
    beyond this point
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    start affecting near-vision
    tasks like reading,
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    and by the time you reach age 60,
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    nothing within a meter
    radius of you is clear.
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    Right now some of you
    are probably thinking,
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    that sounds bad but he means
    you in a figurative sense,
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    only for the people that actually
    end up with presbyopia.
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    But no, when I say you, I literally mean
    that every single one of you
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    will someday be presbyopic
    if you aren't already.
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    That sounds a bit troubling.
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    I want to remind you that presbyopia
    has been with us for all of human history
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    and we've done a lot
    of different things to try and fix it.
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    So to start, let's imagine
    that you're sitting at a desk, reading.
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    If you were presbyopic,
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    it might look a little
    something like this.
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    Anything close by,
    like the magazine, will be blurry.
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    Moving on to solutions.
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    First, reading glasses.
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    These have lenses
    with a single focal power
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    tuned so that near objects
    come into focus.
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    But far objects
    necessarily go out of focus,
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    meaning you have to constantly
    switch back and forth
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    between wearing and not wearing them.
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    To solve this problem
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    Benjamin Franklin invented
    what he called "double spectacles."
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    Today we call those bifocals,
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    and what they let him do
    was see far when he looked up
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    and see near when he looked down.
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    Today we also have progressive lenses
    which get rid of the line
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    by smoothly varying the focal power
    from top to bottom.
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    The downside to both of these
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    is that you lose field of vision
    at any given distance,
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    because it gets split up
    from top to bottom like this.
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    To see why that's a problem,
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    imagine that you're climbing
    down a ladder or stairs.
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    You look down to get
    your footing but it's blurry.
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    Why would it be blurry?
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    Well, you look down
    and that's the near part of the lens,
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    but the next step was past arm's reach,
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    which for your eyes counts as far.
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    The next solution I want to point out
    is a little less common
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    but comes up in contact lenses
    or LASIK surgeries,
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    and it's called monovision.
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    It works by setting up
    the dominant eye to focus far
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    and the other eye to focus near.
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    Your brain does the work
    of intelligently putting together
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    the sharpest parts from each eye's view,
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    but the two eyes see
    slightly different things,
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    and that makes it harder
    to judge distances binocularly.
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    So where does that leave us?
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    We've come up with a lot of solutions
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    but none of them quite restore
    natural refocusing.
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    None of them let you
    just look at something
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    and expect it to be in focus.
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    But why?
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    Well, to explain that
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    we'll want to take a look
    at the anatomy of the human eye.
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    The part of the eye that allows us
    to refocus to different distances
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    is called the crystalline lens.
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    There are muscles surrounding the lens
    that can deform it into different shapes,
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    which in turn changes its focusing power.
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    What happens when someone
    becomes presbyopic?
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    It turns out that
    the crystalline lens stiffens
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    to the point that it doesn't
    really change shape anymore.
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    Now, thinking back
    on all the solutions I listed earlier,
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    we can see that they all have
    something in common with the others
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    but not with our eyes,
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    and that is that they're all static.
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    It's like the optical equivalent
    of a pirate with a peg leg.
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    What is the optical equivalent
    of a modern prosthetic leg?
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    The last several decades have seen
    the creation and rapid development
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    of what are called "focus-tunable lenses."
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    There are several different types.
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    Mechanically-shifted Alvarez lenses,
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    deformable liquid lenses
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    and electronically-switched,
    liquid crystal lenses.
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    Now these have their own trade-offs,
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    but what they don't skimp on
    is the visual experience.
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    Full-field-of-view vision that can be
    sharp at any desired distance.
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    OK, great. The lenses we need
    already exist.
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    Problem solved, right?
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    Not so fast.
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    Focus-tunable lenses add a bit
    of complexity to the equation.
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    The lenses don't have any way of knowing
    what distance they should be focused to.
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    What we need are glasses
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    that, when you're looking far,
    far objects are sharp,
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    and when you look near,
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    near objects come into focus
    in your field of view,
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    without you having to think about it.
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    What I've worked on
    these last few years at Stanford
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    is building that exact intelligence
    around the lenses.
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    Our prototype borrows technology
    from virtual and augmented reality systems
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    to estimate focusing distance.
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    We have an eye tracker that can tell
    what direction our eyes are focused in.
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    Using two of these, we can
    triangulate your gaze direction
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    to get a focus estimate.
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    Just in case though,
    to increase reliability,
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    we also added a distance sensor.
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    The sensor is a camera
    that looks out at the world
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    and reports distances to objects.
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    We can again use your gaze direction
    to get a distance estimate
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    for a second time.
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    We then fuse those two distance estimates
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    and update the focus-tunable
    lens power accordingly.
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    The next step for us was
    to test our device on actual people.
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    So we recruited about 100 presbyopes
    and had them test our device
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    while we measured their performance.
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    What we saw convinced us right then
    that autofocals were the future.
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    Our participants could see more clearly,
    they could focus more quickly
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    and they thought it was an easier
    and better focusing experience
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    than their current correction.
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    To put it simply, when it comes to vision,
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    autofocals don't compromise
    like static corrections in use today do.
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    But I don't want to get ahead of myself.
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    There's a lot of work
    for my colleagues and me left to do.
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    For example, our glasses are a bit --
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    (Laughter)
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    bulky, maybe?
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    And one reason for this
    is that we used bulkier components
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    that are often intended
    for research use or industrial use.
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    Another is that we need
    to strap everything down
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    because current eye-tracking algorithms
    don't have the robustness that we need.
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    So moving forward,
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    as we move from a research
    setting into a start-up,
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    we plan to make future autofocals
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    eventually look a little bit more
    like normal glasses.
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    For this to happen,
    we'll need to significantly improve
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    the robustness
    of our eye-tracking solution.
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    We'll also need to incorporate smaller
    and more efficient electronics and lenses.
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    That said, even with
    our current prototype,
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    we've shown that today's
    focus-tunable lens technology
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    is capable of outperforming
    traditional forms of static correction.
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    So it's only a matter of time.
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    It's pretty clear that in the near future,
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    instead of worrying about which pair
    of glasses to use and when,
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    we'll be able to just focus
    on the important things.
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    Thank you.
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    (Applause)
Title:
Autofocusing reading glasses of the future
Speaker:
Nitish Padmanaban
Description:

As you age, you gradually lose the ability to refocus your eyes -- a phenomenon as old as humanity itself -- leading to a reliance on bifocals, contacts and procedures like LASIK surgery. Electrical engineer Nitish Padmanaban offers a glimpse of cutting-edge tech that's truly a sight for sore eyes: dynamic, autofocusing lenses that track your sight and adjust to what you see, both near and far.

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Video Language:
English
Team:
closed TED
Project:
TEDTalks
Duration:
06:51

English subtitles

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