Outside the limbus, a thick layer of cells called the conjunctiva protects the rest of our eye.

在角膜缘外，一层厚厚的称结膜的细胞保护着我们眼睛的其余部分。

To keep the cornea in perfect condition, a fine layer of cells on its surface are constantly replaced, flowing in from a region called the limbus.

了使角膜保持完美状态，其表面的一层细细胞会不断更换，从称角膜缘的区域流入。

Doctors can take some of the patient's healthy limbus and transplant it, but take too much and they risk causing the same problem at the donor site.

医生可以取一些患者健康的角膜缘并进行移植，但取太多可能会在供体部位引起同样的问题。

If the patient has a small amount of healthy limbus left, doctors can still just take a chunk and amplify the cells in the lab before transplanting them back into the eye.

如果患者只量健康的角膜缘，医生仍可以只取一大块并在实验室中扩增细胞，后再将它们移植回眼中。

The limbus acts as a barrier between the cornea and the conjunctiva but if it gets damaged, the conjunctiva can start to grow across the cornea, clouding the window and cutting out the light.

角膜缘充当角膜和结膜之间的屏障， 但如果它受到损坏，结膜会开始在角膜上生长， 遮蔽窗口并切断光线。

That way there's no rejection and far fewer cells are needed… Sounds good, but it requires specialist equipment and the patient still might not have enough healthy limbus left to work with.

这样就没有排斥反应，需要的细胞也得多… … 听起来不错，但它需要专门的设备，而且患者可能仍没有足够的健康角膜缘来工作。