You hear a lot about LASIK eye surgery, and most know that a laser is used to do it, but very few people know how the whole thing actually works. Below is a very simple description.
When you look at someone else’s eyes, or look at your own in a mirror you see the whites of the eyes and the colored part, which is the iris of course, and then you see the black hole in the middle, the pupil which is of course where the images come through.
If you look closer you can also see that there is something covering your pupil; something clear and shiny. This is your cornea. It is the part of your eye that works with the lens which is behind it, to focus images onto the back of your eye, which in turn converts it into signals that the brain can understand. To be correct there is also another part of your eye, the aqueous humor, which is mostly a thin bag of water and sits between the cornea and the lens. Its purpose is to support the cornea.
LASIK surgery happens on the cornea; that’s it, the very outermost part of your eye that you can touch with your finger if you feel like it.
The whole truth is that LASIK surgery is actually comprised of two parts. The first is where a tiny slice is made into the cornea using a microkeratome machine, which is not a laser but a very tiny knife connected to a machine that helps an eye doctor manipulate it; the slicing creates a very thin flap on the surface of the cornea which is then pulled back and out of the way. The second part is where a laser is used to vaporize some of the surface of the cornea where the flap was just pulled from. This two step process allows the eye doctor to work on the cornea with the laser to change the corneal surface in just the right way so as to cause the images that passes through it to be changed enough to cause the image received in the back of the eye to be better than it was before the procedure; in many cases, to 20/20.
The laser used is a so-called cool laser in that it doesn’t make the cornea get hot, instead it sends a highly focused beam of ultraviolet light which causes a minuscule breakdown in organic matter, namely the surface of a cornea. The beam of light is so small that it is only able to penetrate the corneal surface to a depth of a single nanometer. Thus, the burning away of corneal matter is so small as to be almost immeasurable.
Once the eye doctor finishes reshaping the cornea, the flap is returned to its original location and the procedure is over. Because the cornea heals so quickly there is no need for stitches or band-aids or anything like that. The patient wears protective goggles for a day and uses eye drops to keep things moist, and that’s about it.