The Excimer Laser in Vision Correction
Laser Refractive Surgery became possible, because of the invention of a new kind of laser, called the excimer laser. There are several reasons why the excimer laser can be used for surgery on the cornea. They include:
a) Unlike most lasers, its effect comes not from the conversion of light energy into heat energy, but from using light energy to break the bonds which hold the tissue together. This means that while it can remove tissue from the cornea, it cannot damage the remaining cornea by heat.
b) It is capable of removing precise amounts of tissue from the cornea, with sub-micron accuracy. Typically, the lasers used on the cornea can remove about 0.25 micron of corneal thickness with great accuracy. This is an unprecedented level of accuracy.
c) It leaves behind very smooth surfaces on the cornea.
d) It only removes tissue where it hits the cornea. There is no damage to surrounding areas. So one can remove tissue in a perfect shape that is necessary to correct refractive errors.
When the excimer laser first became available commercially, eye surgeons used it for a procedure known as Photo Refractive Keratectomy or PRK.
Next: Photo Refractive Keratectomy or PRK or Surface Ablation (ASA) or LASEK