How does laser eye surgery work? - Dan Reinstein

譯者: Lilian Chiu 審譯者: Helen Chang

In 1948, Spanish ophthalmologist Jose Ignacio Barraquer Moner

1948 年，西班牙眼科醫生 荷西伊納西歐 · 巴拉凱爾莫尼爾

was fed up with glasses.

受夠了眼鏡。

He wanted a solution for blurry vision that fixed the eye itself,

他希望能找到修復眼睛本身的辦法 來解決視力模糊的問題，

without relying on external aids.

不要再仰賴外部的協助。

But the surgery he eventually devised was not for the faint of heart.

但，他最終設計出來的手術 完全不適合膽小的人。

Barraquer began by slicing off the front of a patient’s cornea

巴拉凱爾一開始先把 病人的角膜前側切下來，

and dunking it in liquid nitrogen.

把它泡在液態氮中。

Using a miniature lathe, he ground the frozen cornea

他用一個迷你車床， 將冰凍的角膜磨成

into the precise shape necessary to focus the patient’s vision.

能夠讓病人視力聚焦的精確形狀。

Then he thawed the disc, and sewed it back on.

接著，他把這個圓盤 解凍後再縫回去。

Barraquer called this procedure keratomileusis,

巴拉凱爾把這種手術 稱為「角膜重塑術」，

from the Greek words for “carving” and “cornea.”

是用希臘字「切刻」 和「角膜」組成的。

And though it might sound grisly, his technique produced reliable results.

雖然他的技巧聽起來 很可怕，結果卻很可靠。

So how did Barraquer’s surgery work?

所以，巴拉凱爾的手術 是怎麼一回事？

Keratomileusis corrects what are called refractive errors:

角膜重塑術會修正 所謂的折射錯誤：

imperfections in the way the eye focuses incoming light.

即眼睛無法完美地 將射入的光線進行對焦。

Ideally, the cornea and lens work together to focus light

理想上，角膜和晶體會合作

將光線聚焦在視網膜表面上，

on the surface of the retina,

but several kinds of refractive errors can impair this delicate system.

但好幾種折射錯誤 都可能妨礙這個脆弱的系統。

In people with myopia, or short-sightedness,

就有近視眼的人來說，

a steep cornea focuses light just short of the retina.

比較陡的角膜會讓光線的 聚焦點無法抵達視網膜。

Those with hyperopia, or far-sightedness, have the opposite problem:

遠視的人則有相反的問題：

light is focused too far beyond the retina.

光線被聚焦的點遠超過了視網膜。

And in people with astigmatism, the cornea has two different curvatures

至於亂視的人，角膜 則有兩種不同的曲度，

which focus light at two distances and produce blurry vision.

會造成兩種光線聚焦的 距離，導致視力模糊。

Even those with perfect vision will eventually suffer from presbyopia,

即使視力完美的人， 將來也會有老花眼，

or “aging eyes.”

即眼睛老化。

As the proteins in the lens age, they slowly increase its size.

水晶體內的蛋白質 老化之後，會慢慢變大。

By an adult’s mid-40’s, the lens is too large

成人到了四十五歲左右， 水晶體就會太大，

to easily change shape and shift focus.

無法輕易改變形狀和轉換焦點。

Glasses and contact lenses bend light to compensate for these refractive errors.

眼鏡和隱形眼鏡會改變光線方向

來補償這些折射錯誤。

But, as Barraquer’s procedure shows,

但，巴拉凱爾的手術證明，

we can also alter the shape of the cornea itself;

我們也能改變角膜本身的形狀；

moving the focal point backwards, forwards,

將焦點向前或向後移動，

or pulling a divided image together.

或者將分開的影像拉疊回來。

And thankfully, modern eye surgeons can sculpt the cornea

謝天謝地，現代的 眼睛外科醫生不需要

with far less invasive tools.

用這麼入侵性的工具 就可以雕塑角膜。

In corrective laser eye surgery, surgeons rely on excimer lasers.

做雷射眼睛矯正手術時，

外科醫生要仰賴準分子雷射。

These tools are accurate enough to etch words into a human hair.

這些工具精確到 能在人類頭髮上刻字。

To safely accomplish these ultra-fine incisions,

為了要能安全完成 這些極細緻的切割，

they use a technique called photoablation.

他們會用一種叫做光剝離的技術。

This allows the laser to essentially evaporate organic tissue

基本上，這種技術讓雷射 能夠將有機組織蒸發，

without overheating surrounding eye tissue.

且不會讓周圍的眼睛組織過熱。

So how does laser eye surgery actually work?

所以，眼睛雷射手術是怎麼做的？

The first step is to separate a thin layer from the front of the cornea.

第一步是從角膜前側 分離出薄薄的一層。

This can be done with either a flat, wide blade, or a femto-second laser

要做到這一點， 可以使用平寬的刀片，

或者飛秒雷射，

that produces millions of tiny plasma bubbles

它可以產生出數百萬個 微小的電漿泡，

to create a plane beneath the corneal surface.

在角膜表面底下創造出一個平面。

Surgeons then lift the flap to expose the inside of the cornea.

接著，外科醫生會將這蓋層 掀起，露出角膜的內部。

Guided by the refractive error and the shape of the cornea,

根據折射錯誤 及角膜的形狀來計算，

the excimer laser robotically sculpts the exposed corneal bed

準分子雷射會機械式地 雕塑出露出來的角膜床，

into the correct shape.

雕成正確的形狀。

This process usually takes less than 30 seconds for each eye.

這個過程通常每隻眼睛 只要花不到三十秒的時間。

Finally, the flap is closed,

最後，再將蓋層闔上，

and its edges reseal themselves in just a few hours.

幾個小時內，它的邊緣 會自行重新封上。

Because the lasering is done on the eyeball itself,

因為雷射手術是在眼球上進行，

it’s described as “in situ,” or “on site.”

這手術會被描述為是「原位」的。

Its complete name is “laser in-situ keratomileusis” –

它的全名叫做「準分子雷射 原位層狀角膜塑形術」——

but you probably know it as LASIK.

大家比較熟的可能是 它的縮寫 LASIK。

Essentially, this technique carves a patient’s contact lens prescription

基本上，這種技術是 將病人的隱形眼鏡處方

直接刻在他們的角膜上。

onto their cornea.

Like any surgical procedure,

和任何外科手術一樣， LASIK 也會有風險。

LASIK comes with certain risks.

Some patients experience slightly blurred vision that can’t be corrected by glasses.

有些病人會發生輕微的 視線模糊，且無法用眼鏡校正。

But the technique is currently about as likely to damage your eyes

但目前這項技術 對眼睛的損害差不多

as wearing daily disposable contact lenses for one year.

等同於配戴拋棄式隱形眼鏡一年。

Today, a technique called SMILE enables surgeons to sculpt the cornea

現今，外科醫生會用一種 叫 SMILE 的技術來雕塑角膜，

through even smaller incisions –

手術的切口會更小， 讓恢復時間更短。

further reducing recovery time.

And lasers aren’t just correcting the three types of refractive errors –

且，雷射不僅能修正 三種折射錯誤——

this technology can also restore aging eyes.

這項技術也能恢復老化的眼睛。

In a technique called Laser Blended Vision,

有一種叫雷射融合校視的技術，

surgeons adjust one eye to be slightly better at distance vision

外科醫生能用它來做微調， 讓一隻眼睛的遠距離視線更好，

and the other to be better at close range vision.

另一隻眼睛則是近距離視線更好。

The difference between the two eyes is small enough

兩眼之間的差距小到

that most patients can merge their vision,

讓大部分的病人 可以合併他們的視線，

allowing both eyes to work together at all distances.

讓雙眼一起看各種不同的距離。

Advances in laser technology continue to make vision correction surgery

雷射技術的持續進步， 讓視力矯正手術

more effective and accessible.

變得越來越有效，也越容易取得。

One day soon, Barraquer’s vision of a world without glasses

在不久的將來，可能就能實現

巴拉峛爾的遠景： 一個沒有眼鏡的世界。

may finally come true.