What is PRK ?
PRK (photorefractive keratectomy) is a type of refractive surgery to correct myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.
PRK was the first type of laser eye surgery for vision correction and is the predecessor to the popular LASIK procedure. Though PRK recovery takes a bit longer than recovery from LASIK eye surgery, PRK is still commonly performed and offers advantages over LASIK for some patients.
Like LASIK and other types of laser eye surgery, PRK works by reshaping the cornea using an excimer laser, allowing light entering the eye to be properly focused onto the retina for clear vision.
The main difference between PRK and LASIK is the first step of the procedures.
In LASIK, a thin flap is created on the cornea with a microkeratome or a femtosecond laser. This flap is lifted to expose the underlying corneal tissue and is replaced after the cornea is reshaped with an excimer laser.
In PRK, the thin outer layer of the cornea (epithelium) is removed and discarded prior to reshaping the underlying corneal tissue with an excimer laser. The epithelium repairs itself (grows back over the corneal surface) within a few days after surgery.
A variation of PRK, called LASEK, also is available. Instead of removing the outer epithelial layer of the cornea as with PRK, LASEK involves lifting the epithelial layer (using a surgical instrument called a trephine), preserving it during surgery and then replacing it on the eye's surface at the end of the procedure.
LASEK has decreased in popularity due to the slower recovery of vision compared with PRK, as the replaced epithelial layer takes longer to recover in LASEK than the growth of a new epithelial layer in PRK.