LASIK 即激光视力矫正手术
LASIK, or laser-assisted in situ keratomileusis,
是最常见的眼睛激光手术
is the most commonly performed laser eye surgery
用来治疗 近视 远视 散光
to treat myopia, hyperopia and astigmatism.
治疗的目的是改造角膜
The goal of the treatment is to reshape the cornea
以矫正折射误差
to correct the refractive error of the eye.
角膜是眼睛前方透明的圆拱形结构
The cornea is the transparent dome-shaped structure in front of the eye.
角膜能够折射光线
The cornea refracts light
且约占眼睛折光能力的三分之二
and accounts for about two-thirds of the eye’s total optical power.
变更角膜的曲率会改变光线进入眼镜的路线
Altering the curvature of the cornea changes the way light rays enter the eye.
因此 光线能够正确聚焦于视网膜以形成更清晰的视野
As a result, the light rays can be focused properly onto the retina for clearer vision.
对于近视的人 激光被用来使角膜变平
For nearsighted people, the laser is usedto flatten the cornea.
对于远视的人 角膜会更加弯曲
For farsighted people, the cornea is madesteeper.
对于散光的病人
For patients with astigmatism,
激光被用来使不规则形状的角膜变平滑
the laser is used to smooth the irregularly-shaped cornea
变成一个更规则的形状
into a more regular shape.
角膜的外层
The outer layer of the cornea –
即上皮细胞 在被破坏或被移除后的几天内
the epithelium is capable of replacing itself within
能够自行更换
a few days after being damaged or removed.
角膜的更深层 即基质
The deeper layer of the cornea – the stroma,
是一种永久性的角膜组织
on the contrary, is a permanent corneal tissue
拥有有限的再生能力
with very limited regenerative capacity.
如果基质被激光改造 基质将无法再改变
The stroma, if reshaped by a laser, will remain that way permanently.
在这一过程中 在角膜表面产生一个薄而圆的角膜瓣
In this procedure, a thin, circular”FLAP”is created in the surface of the cornea to
以进出永久性的角膜组织
gain access to the permanent corneal tissue.
可以用一个叫微型角膜刀的医疗切割工具
This can be done with a mechanical cutting tool called a microkeratome,
或者是用无刀片的飞秒激光来处理
or, for a blade-free experience by a femtosecond laser.
然后准分子激光用来去除
An excimer laser is then used to remove
一些角膜组织来改造角膜
some corneal tissue to reshape the cornea.
准分子激光用冷紫外线束
Excimer laser uses cool ultraviolet light
以精确的方式来消融
beams to vaporize microscopic amounts of tissue
微小的角膜组织来改造角膜
in a precise manner to accurately reshapethe cornea.
准分子激光是由电脑控制的
The excimer laser is computer-controlled and
根据病人屈光不正的情况进行编程
is programmed based on the patient’s refractive error.
角膜瓣被放回原来位置并慢慢痊愈
The flap is then laid back in place and is allowed to heal.
LASIK基本上是无痛的 在几分钟内就能完成
LASIK eye surgery is mostly painless and can be completed within minutes.
一般隔天就能感受到视力的提升
Improved vision can usually be seen overnight.
PRK 即准分子角膜激光切削术
PRK, or photorefractive keratectomy,
是第一种矫正视力的眼睛激光手术
was the first type of laser eye surgery for vision correction
是如今流行的LASIK的前身
and is the predecessor to the popularLASIK procedure.
在PRK中 没有角膜瓣产生
In PRK, no flap is created, rather,
眼睛表面的上皮细胞简单地被移除
the epithelial cells on the eye surfaceare simply removed.
准分子激光用来改造角膜
An excimer laser is then used to reshape the cornea just
正如LASIK的作用
like it does in LASIK.
PRK的视力矫正效果
The vision correction outcomes of PRK surgery are comparable to those
与LASIK效果相当
of LASIK, but the
但是恢复时长更长
recovery period is longer.
这是因为上皮在PRK中被完全移除
This is because the epithelium is completely removed in PRK
需要花费几天时间来再生
in PRK and it takes a few days to regenerate.
接受PRK的病人
PRK patients also have more discomfort and haziness
在术后前几天也有更多的不适和晕眩
of vision in the first few days after the surgery.
也要花费更长时间才能感受到视力的提升
Improved vision also takes longer to achieve.
PRK也有一定的优点
PRK does, however, offer certain advantages.
因为PRK不会生成有上皮和基质组织的皮瓣
Because PRK does not involve creation of a flap, which contains both epithelial and deeper
基质的整体厚度对于治疗来说也是足够的
stromal tissue, the entire thickness of the stroma is available for treatment.
因此治疗范围更广
The treatment range is therefore higher.
尤其适用于高度近视的病人
This is particularly useful for patients with high levels
或对于LASIK来说角膜过薄的病人
of myopia or for those whose cornea is too thin for LASIK.
PRK完全不会有与角膜瓣有关的并发症风险
PRK is also free of flap-related complicationrisks.