Every single one of us will lose

我們每個人都將會或已經失去

or has already lost something we rely on every single day.

某樣我們每天所仰賴的東西。

I am of course talking about our keys.

當然，我說的是我們的鑰匙。

(Laughter)

（笑聲）

Just kidding.

開玩笑的。

What I actually want to talk about is one of our most important senses: vision.

我真的想要談的 是我們最重要的感官之一：

Every single day we each lose a little bit of our ability

視覺。

to refocus our eyes

我們的眼睛每天都會 失去一點點重新對焦的能力，

until we can't refocus at all.

直到我們完全無法重新對焦。

We call this condition presbyopia,

我們將這個狀況稱為老花眼，

and it affects two billion people worldwide.

全世界有二十億患者。

That's right, I said billion.

沒錯，二十億人。

If you haven't heard of presbyopia,

若你從未聽過老花眼，且在納悶： 「這二十億人在哪裡？」

and you're wondering, "Where are these two billion people?"

在開始談細節前先給個提示。

here's a hint before I get into the details.

它就是人們配戴閱讀眼鏡 或雙焦眼鏡的原因。

It's the reason why people wear reading glasses or bifocal lenses.

我先來談談這種對焦能力的喪失， 也就是老花眼的原因。

I'll get started by describing the loss in refocusing ability

剛出生時，你能對焦的 最近距離是 6.5 公分——

leading up to presbyopia.

如果你想要的話。

As a newborn, you would have been able to focus

到了二十五歲上下， 對焦能力只剩下一半，

as close as six and a half centimeters,

十公分左右，但不算差太多， 你不會注意到有差別。

if you wished to.

快要五十歲時，能對焦的最近距離 大約是二十五公分或更遠。

By your mid-20s, you have about half of that focusing power left.

當對焦距離比上述更遠時，

10 centimeters or so,

就會開始影響到 近距離的工作，如閱讀，

but close enough that you never notice the difference.

等到你六十歲時，

By your late 40s though,

一公尺範圍內的東西都看不清楚了。

the closest you can focus is about 25 centimeters,

現在有些人可能在想：

maybe even farther.

聽起來很糟， 但他說的「你」只是比喻，

Losses in focusing ability beyond this point

只是針對以後會有老花眼的人。

start affecting near-vision tasks like reading,

不是的，「你」真的是指每一個人。

and by the time you reach age 60,

就算現在還沒有老花眼， 總有一天都會有。

nothing within a meter radius of you is clear.

聽起來讓人憂慮。

Right now some of you are probably thinking,

要知道，在整個人類歷史中， 老花眼一直與我們同在，

that sounds bad but he means you in a figurative sense,

我們試過很多方法來矯正它。

only for the people that actually end up with presbyopia.

首先，我們來想像一下， 你坐在桌前閱讀。

But no, when I say you, I literally mean that every single one of you

如果你有老花眼， 看起來可能會像是這樣。

will someday be presbyopic if you aren't already.

任何太近的東西， 像這本雜誌，都會模糊掉。

That sounds a bit troubling.

接著，解決方案：

I want to remind you that presbyopia has been with us for all of human history

第一，用閱讀眼鏡。

and we've done a lot of different things to try and fix it.

這副用的是單焦點鏡片，

So to start, let's imagine that you're sitting at a desk, reading.

能對焦在鄰近的物體上。

If you were presbyopic,

但遠處的物體就一定會模糊掉，

it might look a little something like this.

也就是說，你得要一下戴上眼鏡，

Anything close by, like the magazine, will be blurry.

一下把眼鏡拿下來。

Moving on to solutions.

為了解決這個問題，

First, reading glasses.

班傑明．富蘭克林發明了 他所謂的「雙光眼鏡」，

These have lenses with a single focal power

現今我們稱為雙焦眼鏡。

tuned so that near objects come into focus.

戴上這種眼鏡的， 向上看時就可以看遠處，

But far objects necessarily go out of focus,

向下看則可以看近處。

meaning you have to constantly switch back and forth

現今，我們有漸層鏡片， 中間不會有接縫的線，

between wearing and not wearing them.

從上而下的折射度會漸漸改變。

To solve this problem

這兩種眼鏡的不利之處 在於你會失去任何距離的視野，

Benjamin Franklin invented what he called "double spectacles."

因為視野會像這樣從上而下切分開來。

Today we call those bifocals,

若要了解這個問題， 想像你在爬下梯子或樓梯。

and what they let him do was see far when he looked up

你向下看你的立足點，但很模糊。

and see near when he looked down.

它為什麼會模糊？

Today we also have progressive lenses which get rid of the line

你向下看時， 用到鏡片上看近處的區域，

by smoothly varying the focal power from top to bottom.

但下一步在你手臂能及的範圍之外，

The downside to both of these

對你的眼睛來說是遠處。

is that you lose field of vision at any given distance,

下一個解決方案沒那麼常見，

because it gets split up from top to bottom like this.

但在隱形眼鏡或 LASIK 手術中 會提到，那就是單眼融視。

To see why that's a problem,

它的做法是設定 主導的眼睛對焦在遠處，

imagine that you're climbing down a ladder or stairs.

另一眼對焦在近處。

You look down to get your footing but it's blurry.

大腦會很聰明地將兩眼所見中 輪廓最鮮明的部分組合起來，

Why would it be blurry?

但因為兩眼所見略有不同， 雙眼一起看時會較難判斷距離。

Well, you look down and that's the near part of the lens,

那我們還能怎麼辦？

but the next step was past arm's reach,

我們想出了許多解決方案，

which for your eyes counts as far.

但沒有一種能恢復 天生的重新對焦能力。

The next solution I want to point out is a little less common

沒有讓你眼睛看任何事物 都能自動對焦的方法。

but comes up in contact lenses or LASIK surgeries,

但為什麼？

and it's called monovision.

要解釋這一點，就要來談談 人類眼睛的解剖學。

It works by setting up the dominant eye to focus far

眼睛中讓我們能根據不同距離 重新對焦的部分叫做水晶體。

and the other eye to focus near.

水晶體周圍有肌肉，

Your brain does the work of intelligently putting together

能讓它變成不同的形狀，

the sharpest parts from each eye's view,

因而改變它的折射率。

but the two eyes see slightly different things,

有老花眼時會如何？

and that makes it harder to judge distances binocularly.

水晶體會變硬，

So where does that leave us?

到了無法再改變形狀的程度。

We've come up with a lot of solutions

回想一下剛才列出的所有解決方案，

but none of them quite restore natural refocusing.

這些方案彼此間都有些共通點，

None of them let you just look at something

和眼睛卻沒有共通點，

and expect it to be in focus.

因為它們都是靜態不變的，

But why?

如果用義肢來打比方， 就像是海盜的木樁腿。

Well, to explain that

那麼眼睛版本的現代義肢是什麼？

we'll want to take a look at the anatomy of the human eye.

我們所謂的｢可調焦鏡片｣出現後， 在過去數十年間快速發展。

The part of the eye that allows us to refocus to different distances

類型有好幾種：

is called the crystalline lens.

機械轉換式的 Alvarez 鏡片、 可變形的液體鏡片，

There are muscles surrounding the lens that can deform it into different shapes,

以及電子切換液晶鏡片。

which in turn changes its focusing power.

每一種都有好有壞， 但視覺體驗都不打折扣。

What happens when someone becomes presbyopic?

在任何想要的距離， 都能有清晰的全景視野。

It turns out that the crystalline lens stiffens

好極了。已經有了我們需要的鏡片。

to the point that it doesn't really change shape anymore.

問題解決。對吧？

Now, thinking back on all the solutions I listed earlier,

沒那麼快。

we can see that they all have something in common with the others

可調焦鏡片為此技術的發展 帶來了一些複雜的因素。

but not with our eyes,

鏡片本身不會知道 它們應該對焦在什麼距離上。

and that is that they're all static.

我們需要的眼鏡，

It's like the optical equivalent of a pirate with a peg leg.

是讓你在看遠處時，遠處物體很清晰，

What is the optical equivalent of a modern prosthetic leg?

當你看近處時，

The last several decades have seen the creation and rapid development

近處物體能在你的視野中對焦， 而你連想都不用想就能辦到。

of what are called "focus-tunable lenses."

過去幾年我在史丹佛大學研究的

There are several different types.

正是賦予這種鏡片智慧。

Mechanically-shifted Alvarez lenses,

我們的原型借用了 虛擬和擴增實境系統的技術，

deformable liquid lenses

來估計對焦的距離。

and electronically-switched, liquid crystal lenses.

我們有眼睛追蹤器， 能辨別眼睛對焦的方向。

Now these have their own trade-offs,

有了這兩者，我們就能用三角定位 找出凝視方向，以估計焦點。

but what they don't skimp on is the visual experience.

不過，以防萬一，

Full-field-of-view vision that can be sharp at any desired distance.

我們還加上距離感測器來增加可靠度。

OK, great. The lenses we need already exist.

感測器是對準外在世界的攝影機， 能回報物體的距離。

Problem solved, right?

我們就可以再次使用你的凝視方向 取得第二個距離估計值。

Not so fast.

接著將兩個距離估計值結合，

Focus-tunable lenses add a bit of complexity to the equation.

再依此調校可調焦鏡片的折射度。

The lenses don't have any way of knowing what distance they should be focused to.

我們的下一步是要讓真人 來測試我們的裝置。

What we need are glasses

所以我們招募了一百名 有老花眼的人來測試，

that, when you're looking far, far objects are sharp,

並測量他們的表現。

and when you look near,

我們看到結果的當下 就讓我們深信自動對焦就是未來。

near objects come into focus in your field of view,

受試者能看得更清楚， 能更快速對焦，

without you having to think about it.

他們認為這比他們目前 用的視力矯正更容易也更棒，

What I've worked on these last few years at Stanford

簡單來說，

is building that exact intelligence around the lenses.

自動對焦不像現今使用的 靜態視力矯正方式，

Our prototype borrows technology from virtual and augmented reality systems

會在視力方面妥協。

to estimate focusing distance.

但我不想把話講得太滿。

We have an eye tracker that can tell what direction our eyes are focused in.

我和同事還有很多事要做。

Using two of these, we can triangulate your gaze direction

比如，現在這個眼鏡有點兒——

to get a focus estimate.

（笑聲）

Just in case though, to increase reliability,

笨重嗎？

we also added a distance sensor.

原因是我們使用笨重的元件，

The sensor is a camera that looks out at the world

它們通常是研究用或工業用的。

and reports distances to objects.

另一個原因是所有東西 都要固定，不能晃動，

We can again use your gaze direction to get a distance estimate

因為目前的眼睛追蹤演算法 還沒有我們需要的穩定度。

for a second time.

所以，當我們要從研究環境 跨越至產業環境，創立公司，

We then fuse those two distance estimates

我們未來打算要製造出 看起來像正常眼鏡的自動對焦眼鏡。

and update the focus-tunable lens power accordingly.

要實現這個目標，

The next step for us was to test our device on actual people.

我們得要大大改善 視線追蹤解決方案的穩定度。

So we recruited about 100 presbyopes and had them test our device

我們也需要整合體積更小 且更有效率的電子裝置和鏡片。

while we measured their performance.

儘管如此，我們目前的原型

What we saw convinced us right then that autofocals were the future.

已經證明了現今的可調焦鏡片技術

Our participants could see more clearly, they could focus more quickly

有能力超越傳統形式的靜態視力矯正。

and they thought it was an easier and better focusing experience

只是時間問題。

than their current correction.

顯然，在不久的將來，

To put it simply, when it comes to vision,

我們不用再擔心何時該戴哪副眼鏡，

autofocals don't compromise like static corrections in use today do.

只要專心聚焦在重要的事物上即可。

But I don't want to get ahead of myself.

謝謝。

There's a lot of work for my colleagues and me left to do.

（掌聲）

For example, our glasses are a bit --

(Laughter)

bulky, maybe?

And one reason for this is that we used bulkier components

that are often intended for research use or industrial use.

Another is that we need to strap everything down

because current eye-tracking algorithms don't have the robustness that we need.

So moving forward,

as we move from a research setting into a start-up,

we plan to make future autofocals

eventually look a little bit more like normal glasses.

For this to happen, we'll need to significantly improve

the robustness of our eye-tracking solution.

We'll also need to incorporate smaller and more efficient electronics and lenses.

That said, even with our current prototype,

we've shown that today's focus-tunable lens technology

is capable of outperforming traditional forms of static correction.

So it's only a matter of time.

It's pretty clear that in the near future,

instead of worrying about which pair of glasses to use and when,

we'll be able to just focus on the important things.

Thank you.

(Applause)