What are those floaty things in your eye? - Michael Mauser

浮在眼睛前面的是什麼東西？- 麥可．毛瑟

譯者: Marssi Draw 審譯者: Geoff Chen

Have you ever noticed something swimming in your field of vision?

你有沒有注意到 視野裡有東西游來游去？

It may look like a tiny worm or a transparent blob,

看起來可能像隻小蟲 或是透明的污點

and whenever you try to get a closer look, it disappears,

而且只要你定睛一看 就會不見蹤影

only to reappear as soon as you shift your glance.

只要你轉移視線就又會出現

But don't go rinsing out your eyes!

但你可別跑去洗眼睛了！

What you are seeing is a common phenomenon

你看到的是很普通的現象 稱為飛蚊症

known as a floater.

The scientific name for these objects is Muscae volitantes,

這些東西的學名是 Muscae volitantes

Latin for "flying flies,"

就是拉丁語中「飛蠅」的意思

and true to their name, they can be somewhat annoying.

而且正如其名 它們也挺惱人的

But they're not actually bugs or any kind of external objects at all.

但那可不是真的蟲 也根本不是外界物體

Rather, they exist inside your eyeball.

相反的，那存在於你的眼球之中

Floaters may seem to be alive, since they move and change shape,

飛蚊看起來像活的 畢竟它們會動又會變形

but they are not alive.

但它們不是活的

Floaters are tiny objects that cast shadows on the retina,

飛蚊這種小東西 會投射陰影在視網膜上

the light-sensitive tissue at the back of your eye.

就是在你眼睛後面的光敏組織

They might be bits of tissue,

可能是一些組織

red blood cells,

紅血球

or clumps of protein.

或蛋白質塊

And because they're suspended within the vitreous humor,

因為它們飄浮在透明液中

the gel-like liquid that fills the inside of your eye,

就是在填滿眼睛的膠狀液體中

floaters drift along with your eye movements,

飛蚊跟著你的眼睛一起移動

and seem to bounce a little when your eye stops.

而且眼睛一停 好像會彈回一點

Floaters may be only barely distinguishable most of the time.

飛蚊可能不太明顯 通常是如此

They become more visible the closer they are to the retina,

但它們越靠近視網膜 就會變得越清楚

just as holding your hand closer to a table with an overhead light

就像頭頂有燈的時候 只要你的手越靠近桌面

will result in a more sharply defined shadow.

影子就會越清晰

And floaters are particularly noticeable

飛蚊要非常明顯的話

when you are looking at a uniform bright surface,

就要看著完全明亮的表面

like a blank computer screen,

就像一片空白的電腦螢幕

snow,

雪

or a clear sky,

或是清澈的天空

where the consistency of the background makes them easier to distinguish.

整面相同的背景讓它們更加明顯

The brighter the light is, the more your pupil contracts.

燈越亮，你的瞳孔就會收縮

This has an effect similar to replacing a large diffuse light fixture

這個作用像把較大 且光源四散的吊燈

with a single overhead light bulb,

換成比較小的單一燈泡

which also makes the shadow appear clearer.

也能讓影子看起來更清楚

There is another visual phenomenon that looks similar to floaters

還有另一個視覺現象 看起來像飛蚊症

but is in fact unrelated.

但其實毫無關連

If you've seen tiny dots of light darting about

如果你看到一些小點點的光

when looking at a bright blue sky,

在你看明亮藍天時四處投射

you've experienced what is known as the blue field entoptic phenomenon.

你會感覺到俗稱的謝瑞爾氏現象

In some ways, this is the opposite of seeing floaters.

就某方面來說 這和看到飛蚊的情況相反

Here, you are not seeing shadows

這種時候你看到的不是陰影

but little moving windows letting light through to your retina.

而是移動的小窗口 會讓光穿透進你的視網膜

The windows are actually caused by white blood cells

小窗口其實是白血球造成的

moving through the capillaries along your retina's surface.

白血球會沿著視網膜表面的微細管移動

These leukocytes can be so large that they nearly fill a capillary

這些白血球可以大到 幾乎填滿整個微血管

causing a plasma space to open up in front of them.

讓它們前面的血漿空間擴大

Because the space and the white blood cells

因為白血球裡的空間

are both more transparent to blue light

較能讓藍光穿透

than the red blood cells normally present in capillaries,

而一般微血管裡的紅血球則較難穿透

we see a moving dot of light wherever this happens,

只要這個情況發生 我們就會看到移動的亮光

following the paths of your capillaries and moving in time with your pulse.

跟著你微血管的路徑 並隨著你的脈搏移動

Under ideal viewing conditions,

在視野理想的情況下

you might even see what looks like a dark tail following the dot.

你也許還能看到 一條黑色的尾巴跟在點點後面

This is the red blood cells that have bunched up behind the leukocyte.

這是紅血球 串連在白血球之後

Some science museums have an exhibit which consists of a screen of blue light,

有些科學博物館會有樣本 由藍光螢幕組成

allowing you to see these blue sky sprites much more clearly than you normally would.

讓你能看到這些藍天小精靈 比你平常看到的還清楚

While everybody's eyes experience these sort of effects,

雖然每個人的眼睛都會碰到這些作用

the number and type vary greatly.

但是數量和型態會大不相同

In the case of floaters,

飛蚊症的情況

they often go unnoticed, as our brain learns to ignore them.

通常會不被注意 因為我們的大腦會學著忽視它

However, abnormally numerous

然而數量太多

or large floaters that interfere with vision

或是太大的飛蚊 若是會阻礙視覺

may be a sign of a more serious condition, requiring immediate medical treatment.

那就可能是更嚴重的疾病徵兆 需要立刻做治療

But the majority of the time entoptic phenomena,

但是通常眼內的現象

such as floaters and blue sky sprites,

像是飛蚊和藍天小精靈

are just a gentle reminder that what we think we see

只是溫柔地提醒我們 自己看到的東西

depends just as much on our biology and minds

也同樣需要取決於我們生理和心理

as it does on the external world.

就和外在世界的影響一樣重要