PRK is useful for treating low to moderate levels of myopia or hyperopia with and without astigmatism. It is often the laser vision correction procedure of choice for people with thinner corneas and for individuals who may have certain corneal dystrophies, certain corneal scars, or a condition called "recurrent corneal erosion". Some refractive surgeons prefer PRK over LASIK for all their patients because there is no risk of a flap complication with PRK.
PRK differs from LASIK only in the first step of the procedure. In PRK, instead of creating a corneal flap, the surgeon completely removes the thin outer layer of the cornea (called the epithelium) over the treatment area. The second step of PRK is identical to LASIK: an excimer laser is used to reshape the underlying corneal tissue.
After the laser ablation, a soft contact lens is placed over the eye as a bandage while the corneal epithelium grows back in place, which usually takes about 3 to 5 days. During this period, the patient usually experiences mild to marked discomfort with blurry vision. Because of the greater amount of tissue healing that needs to take place after PRK, it can take from a week to ten days before vision is clear and stable after the procedure.
The post-operative discomfort and longer time required for corneal healing and visual recovery are reasons why PRK is not as popular as LASIK. Still, in some cases PRK offers advantages over LASIK, and the final visual outcomes of PRK are usually equal to those of LASIK.
EPILASIKEPILASIK is an innovative new procedure designed to restore natural vision with the help of an epikeratome. The Epi-Lasik surgeon uses an epikeratome, a separator that creates an epithelial sheet, to make a thin flap in the epithelium. The excimer laser beam is then applied under the epithelial flap to successfully correct refractive errors and restore clear vision.
Advantages of EpiLASIK
Laser epithelial keratomileusis, or LASEK, is a newer form of laser vision correction that combines many of the benefits of the two most commonly performed procedures -- LASIK and PRK. It is used to treat astigmatism, nearsightedness or farsightedness. In LASEK, the epithelium, or outer layer of the cornea, is cut not with the microkeratome cutting tool used in LASIK, but with a finer blade called a trephine and a 20% alcohol solution.Advantages of LASEK
Disadvantages of LASEK