Laser Assisted in-situ Keratomiliusis
Originally, laser vision correction (PRK), while an excellent procedure, was associated with a number of days of blurred vision and moderate discomfort. LASIK was developed to reduce both healing time and post-op discomfort.
All laser vision correction procedures work by reshaping the patient’s cornea so that light is focused onto the retina. Any changes made to the surface layer of the cornea (epithelium) will be temporary, so LASIK must be performed on the sub-epithelial layer of the cornea (stroma). To reach the stroma, the epithelium must be either removed or temporarily displaced. In the original laser vision correction surgery (PRK), the epithelium was simply removed so that the underlying stroma could be reshaped. It then took 5-7 days for the epithelium to regenerate. For these 5-7 days, most patients had blurred vision and moderate discomfort.
LASIK was developed to make laser vision correction easier for the patient. The concept is simple. Why not replace the epithelium after the cornea is reshaped? The problem is, that once the epithelium is removed (or even loosened) it will not stick back to the surface of the cornea. This is because the laser also removes Bowman’s layer, which is the glue that holds the epithelium to the stroma. However, if, we create a thin “flap” of superficial cornea that includes both the epithelium and Bowman’s layer, it will reattach to the reshaped cornea quickly and firmly. And that is how LASIK came to be. With LASIK, a small flap of cornea with the epithelium, Bowman’s layer and a very thin layer of stroma is lifted off the cornea, the laser treatment is performed and the flap is replaced. Over 90% of the epithelium is replaced using the LASIK technique so healing time and discomfort are significantly reduced. When the flap is replaced it will immediately stick back to can rub their eyes, use make-up, open their eyes under water and resume normal activity within 10 days of surgery.