and 50% of people who have it don't even know they do.

然而 50% 得到青光眼的人卻都不知情。

That's because it often has few symptoms

因為青光眼會有些症狀，

and these symptoms can appear after it's too late.

而這些症狀的出現都是為時已晚。

So why is this such a stealth disease?

那為什麼這是個癮性的疾病？

There are two main types of Glaucoma:

青光眼有兩種類型

open angle and closed angle.

開角度與閉合角度

Open angle is the most common and tends to be less severe.

開角度是比較常見的，比較沒那麼嚴重。

It can develop slowly, over time, and go largely undetected unless it's routinely screened for.

它形成的速度比較慢，隨著時間流逝，基本上是感覺不出來，除非平時有在做例行性檢查。

Closed angle, while less common - can appear suddenly and be quite painful.

閉合角度，相對的就比較少見，它會突然出現且非常地疼痛。

Both can eventually can lead to vision loss.

兩者都會導致失明。

- My name's John Flanagan, I'm a professor

我的名字是 John Flanagan，我是一位

at the School of Optometry at the University of California, Berkeley.

加利福尼亞大學柏克萊分校，視光學系的教授。

I'm also dean of the School of Optometry there.

我也是視光學系的院長。

And for the last 40 years I've spent a lot of time researching into the problem of glaucoma.

40 年來我在青光眼的問題上投入了很多時間。

So glaucoma is a neurodegenerative disease,

青光眼是個神經退化疾病，

probably the world's most common neurodegenerative disease,

是世界上最常見的神經退化疾病，

but it's really very specific to the eye.

特別是針對眼睛。

To understand Glaucoma, it helps to know the basics of how the eye works.

了解青光眼，也會讓我們知道眼睛的基本運作。

When light reflects an object, it enters your eye, and its first stop is the cornea.

當光線反射到一個物體上，它會進入你的眼睛，首先會接觸到我們的角膜。

Then it's on through the pupil and ultimately the retina where the image is communicated

接著會通過瞳孔，最後會到視網膜，也就是大腦透過視神經

with your brain by way of the optic nerve.

互相傳達影像的地方。

It's then interpreted as what you see.

也就是轉換成你所看到的東西。

And all of this action is aided by the presence of clear fluids and a complex network of nerves.

這所有的運作都是由眼睛裡透明液體與複雜的網絡神經偕同輔助的。

If you just think for a moment about the eye, and we have this layer called the

你稍微想一下，我們的眼睛都有這一層稱作角膜的東西

cornea where you would put a contact lens, for example, that's clear.

就你是你戴隱形眼鏡時會接觸到的，例如，很透明的。

And it has to be clear, otherwise light can't get in and we can't see.

它必須是很透明的，不然光線會進不來，我們會看不到。

Therefore it can't have blood and blood vessels throughout it feeding that tissue.

也因此它沒有血液，沒有血管來供給細胞組織。

So the way that the eye feeds that tissue is by producing this fluid with all the nutrients;

所以眼睛才會自體產生養分液體

the oxygen and different nutrients bathe the back to help feed it.

浸泡著氧氣和不同的養分液體幫助供給細胞組織。

This all takes place in a network of fibers that surround the wall of the eye

這供給的運作是由圍繞在眼壁的纖維網

and funnel into the optic nerve.

傳輸到到視神經。

When the fluid at the front of the eye stops draining efficiently, pressure increases.

當眼睛外層開始停止有效排水時，壓力會增加。

This can cause problems with blood flow to the optic nerve, which

這會對視神經的血流造成問題，

kills off nerve fibres.

並破壞纖維網。

The eye, to stay in the correct shape, needs fluid to keep it inflated.

眼睛要維持正確的形狀，需要液體讓它保持膨脹。

We need pressure in the eye because otherwise it would collapse.

我們眼睛需要壓力，不然會支撐不住。

So it's always this balance between the pressure inside the eye and the pressure in our capillaries.

所以眼睛裡裡的壓力與毛細血管壓力會一直維持在一個平衡。

And for most of our lives, that balance is fine.

對於大部分的生命，平衡是好的。

But as we get older, the blood supply may become obstructed, and the fluid drainage not as efficient.

但隨著年紀增長，血液供應受阻，液體排放效率變差。

This extra fluid increases the pressure on your eye, which in turn damages the cells

多於液體提升了眼壓，反而破壞細胞組織

and fibers that make up your optic nerve which then leads to vision loss.

以及破壞組成視神經的纖維，它會讓你失明。

This is glaucoma.

這就是青光眼。

The most prone area, the areas that we expect damage first are actually fibers that come

最脆弱的區域，會最先受到損害的區域其實是

in from peripheral vision, the damage happens more with these big fibers as they loop into the top and bottom.

周邊視覺的纖維，當他們進到循環上方與下方時，損壞多數是這些大的纖維。

So 12 o'clock and 6 o'clock on the optic nerve,

所以是視神經是在 12 點鐘與 6 點鐘，

they're the ones that seem to be most prone

它們才是最容易受到青光眼的損壞

to this damage in glaucoma and die off first,

會最先死亡，

and give us very specific patterns of loss in the eye.

且會給我們造成特定的失明模式。

You'd think with drainage problems and eye pressure, you would feel it,

你會認為一切都是排水問題以及你所感受到到的眼壓

but that's not always the case.

但也不全然都是。

That's what makes the symptoms of Glaucoma so difficult to recognize.

因為青光眼的症狀沒這麼好被查覺到，

If your disease is more advanced, in primary open angle glaucoma you would just start to

如果你的病情已經發展了一陣子，且是開角度的，你便會開始注意到

notice areas of vision missing.

部分是視覺已失去。

Or you know, you miss that person walking on the sidewalk or across the street initially.

或者，一開始你會看不見走在路邊或是過馬路的人。

So they can be quite subtle.

它們是相當細微的。

You really don't feel pain other than in the much rarer acute angle glaucoma attacks.

除非是眼比較罕見的銳角青光眼，不然你不會感覺到疼痛。

And it's not that you just feel no pain, your brain is actually overcompensating, adding

那也不是不會痛就沒事，你的大腦其實在過度補償，

to the illusion that nothing is wrong.

添增錯覺。

We often have this idea that if somebody is going blind or losing vision that they

我們常有這種想法，如果別人要瞎了或是失明

have sort of dark or gray areas in their vision.

他們部份的視覺會是黑色或灰色的。

And it just doesn't happen like that.

但並不是像我們所想的這樣。

Most of the time these sort of diseases, particularly glaucoma, will slowly affect small areas of

大部分所謂的疾病，特別是青光眼，會緩慢影響小部份的視覺，

vision, and affect them unequally in the two eyes.

會不平均的影響在兩隻眼睛上。

So your brain is very good at merging what we receive, the view of the outside world

你的頭腦善於合併我們眼睛所接收到的畫面，外面世界的畫面，

from each eye, and merges them together to give our percept of the world.

並將他們合併在一起，給予我們對世界的認知。

Just as an example, if you're looking at a house,

例如，你正在看著一間房子，

and the house has five windows and two doors,

那房子有 5 個窗戶、2 個門，

if you have glaucoma, your brain would make you see that house

如果你有青光眼，你的大腦會讓你看到那房子

just as well as anybody else.

跟一般人沒有兩樣。

But two of the windows might be missing.

但會有 2 個窗戶消失。

Your brain would fill in the brick work or the siding

你的大腦會填補磚瓦或補外牆，

and you would just misinterpret

然後你會對你實際看到的場景

the actual scene that you're looking at.

有所誤解。

So the brain just has this amazing ability to help you feel as though nothing's wrong

所以當你的大腦形成這些缺陷時，它有這神奇的能力

as you develop these defects.

幫助你覺得沒有什麼錯覺。

So since there are very few symptoms with Glaucoma,

因為青光眼的症狀非常少，

you can't identify it on your own.

你無法自己確認。

And your brain is filling in the gaps.

你的大腦一直在填補這些漏洞。

So, how do you know if you have it?

那你要如何知道你有青光眼呢？

Routine screenings and knowing your risk factors, such as family history and high eye pressure, are a start.

例行檢查，了解你的風險因子，像是家族病史與高眼壓都是很好的開始。

And treatment, if caught early, can include drops, medication, laser and other surgeries.

在治療方面，發現得早，可以使用眼藥水、藥物、雷射、以及其他相關手術。

One treatment however, doesn't appear to pass the smell test, just yet.

有一項治療方式，似乎還沒有通過真實性。

We know that marijuana will actually reduce the pressure in the eye.

我們知道大麻其實可以降低眼壓，

The problem is, it's very quick and very short-lived.

但問題是它的效用是短暫的。

So the therapeutic value of marijuana is a complete failure for glaucoma.

所以大麻的治療價值對青光眼完全是沒有用的。

You would literally just have to be smoking continuously

你會得要一直吸菸

to have an effect that might be therapeutic.

來維持治標不是本的作用。

So that's a very long-winded way of saying, don't bother with marijuana with your glaucoma.

雖然是個非常冗長的說法，但對你的青光眼完全不用去考慮大麻。

But there is some hope on the horizon.

但還是有希望曙光。

Especially when it comes to neurological disorders, and Glaucoma is in that category.

特別是講道神經系痛疾病，青光眼正屬於這類型的。

We're seeing all sorts of really amazing discoveries about neurodegenerative disease and glaucoma.

我們看過個種關於神經退化與青光眼的新發現，

that opens up the potential for new therapeutic

對於能停止傷害的新治療方法

treatments that will arrest the damage.

打開了潛在的可能性。

I think there's genuine reason for optimism that we'll start having some treatments for

我認為比較樂觀的部分是，我們對於整體神經退化疾病

neurodegenerative disease as a whole.

將會有治療的方法。

And specifically for glaucoma.

特別是青光眼。