The principle of refractive surgery to correct myopia 1, LASIK is currently the most commonly used surgical procedure worldwide, using a corneal microdebrider instrument to cut a corneal flap placed on the side of the cornea, with a laser scan of the exposed corneal stroma, then the corneal flap reset, and make the flap adhesion fit. Discomfort is minimal and vision recovery is rapid, usually taking only 1-2 days. There are some risks associated with the creation of the corneal flap. 2, LASEK 3 years ago originated in Italy, LASEK surgery does not need to cut the corneal flap, using drugs to push the surface layer of the cornea to the side of the cornea, and then laser scanning in the corneal surface to reset to the original position, postoperative wear corneal contact lenses for about 3-5 days. Discomfort is mild to moderate (mainly light sensitivity) and vision recovery is slow. Avoids the risk of cutting the cryptic flap of LASIK, but may have HAZE (corneal opacity). 3.INTACS (corneal stromal ring) A small peripheral corneal channel is made and a semicircular ring of polymeric material is implanted into the channel without loss of corneal tissue, the implanted ring can be removed at any time after surgery, with minimal discomfort and fast vision recovery, limited to patients with low myopia (currently requiring less than 3D). 4.RK (radioactive keratotomy) A gemstone knife is used to make an incision in the periphery of the cornea, with fast vision recovery and minimal discomfort. However, the scar tissue formed after the healing of the corneal radiolucent incision after surgery is a serious hidden problem. 5.PTK is used to treat irregular or superficial corneal scars on the surface of the cornea. The laser scan is used to smooth the cornea with mild to moderate discomfort. 6.Lamellar keratoplasty The donor cornea is used to replace the diseased part of the patient’s cornea, and the diseased part of the cornea is removed with laser or other instruments, and the vision is restored indefinitely. All of the above surgical methods are applicable to some patients, while some patients are only applicable to one method, and PRK is now eliminated. LASEK is suitable for some patients who previously could not undergo LASIK due to insufficient corneal thickness. The most common complaint of patients after LASEK and LASIK is dry eyes.