LVC is usually performed in one of two ways: on the surface of the cornea – surface ablation – or in the middle of the cornea – LASIK. Both are effective ways of correcting vision and each way has advantages over the other.
In surface ablation the laser energy is applied directly to the surface of the cornea. There are several different techniques used to perform surface ablation. These include PRK, LASEK and Epi-LASIK. The methods differ only in the way in which a thin protective cellular layer called the corneal epithelium is removed before applying the laser energy.
With PRK, either a brush or the EXCIMER laser itself is used to remove the epithelium whereas in LASEK it is removed by ethyl alcohol. In EpiLASIK the epithelium is removed by a machine that uses a plastic separator.
The advantages of surface ablation over LASIK procedures include a stronger cornea and no potential for problems associated with the flap. LASIK has the advantage of faster healing and recovery of vision and a slightly lower risk of infection. Both are effective and reliable methods of correcting vision.
There is another way that vision correction surgery can be performed without removing corneal tissue. The procedure, using an implantable acrylic device called Intacs, involves using the Intralase femtosecond laser to place thin ring segments in the cornea flattening the cornea to treat myopia and astigmatism. Intacs can be used to treat lower levels of nearsightedness and have the advantage that they can be removed. They can also be used to treat certain corneal diseases such as keratoconus.