What are the causes of laser surgery?

At present, there are three main surgical methods for myopia laser surgery: the first is excimer laser surgery, which requires a corneal flap to be made by mechanical keratome, and then under the corneal flap, the corneal stroma is cut by excimer laser, thus changing the corneal curvature and correcting myopia. The second is semi-femtosecond laser surgery, which is to make a corneal flap by femtosecond laser, and then use excimer laser to cut the cornea under the corneal flap. The third type, full femtosecond laser surgery, does not need to make corneal flap, after femtosecond laser directly cut the corneal curvature that needs to be changed in the corneal stroma, and then make a tiny incision, the cut corneal stroma tissue is removed, and the surgery is completed.