Have you ever noticed something swimming in your field of vision?
你是否会注意到自己的视线中有漂浮物？
It may look like a tiny worm or a transparent blob,
它看起来像是小虫或者透明液滴，
and whenever you try to get a closer look, it disappears, only to reappear as soon as you shift your glance.
但当你想要更仔细地看它的时候它又消失了转换视线之后它又会出现。
But don't go rinsing out your eyes!
但你别去冲洗眼睛！
What you are seeing is a common phenomenon known as a floater.
你看的其实是一种常见现象，飞蚊症。
The scientific name for these objects is Muscae volitantes,
科学界称之为Muscae volitantes，
Latin for "flying flies," and true to their name, they can be somewhat annoying.
是拉丁语中飞蚊的意思物如其名，它们有时很讨厌。
But they're not actually bugs or any kind of external objects at all.
但它们不是真正的虫或者身外之物。
Rather, they exist inside your eyeball.
它们就存在于你的眼球中。
Floaters may seem to be alive, since they move and change shape, but they are not alive.
因为“飞蚊”会不断地变形，所以人们会觉得它们是有生命的其实不是。
Floaters are tiny objects that cast shadows on the retina, the light-sensitive tissue at the back of your eye.
“飞蚊”是一种极小的物质，投影于视网膜也就是眼球后部的光敏组织。
They might be bits of tissue, red blood cells, or clumps of protein.
它们可能是小块组织，红细胞或是蛋白质团。
And because they're suspended within the vitreous humor, the gel-like liquid that fills the inside of your eye,
由于它们悬浮于玻璃体，也就是眼内的胶状组织“飞蚊”，
floaters drift along with your eye movements, and seem to bounce a little when your eye stops.
会随眼球而移动，眼球停止转动时它又会少许地弹动。
Floaters may be only barely distinguishable most of the time.
“飞蚊”大多数时候不易被察觉。
They become more visible the closer they are to the retina,
当它们靠近视网膜时，
just as holding your hand closer to a table with an overhead light will result in a more sharply defined shadow.
它们变得可看见这就相当于你把手放在吊灯下更接近桌子时手的阴影会更明显。
