PRK is the acronym for photorefractive keratectomy, which is a variation of refractive surgery in which the epithelium (surface layer) of the cornea is gently wiped away and then an excimer laser is used to reshape the surface of the cornea.

This "cool laser" produces a beam of light that removes microscopic corneal layers, usually only 10-15% of the cornea's total thickness. The process is known as photo ablation, and it changes the shape of the cornea, resulting in an image which is more finely focused on the retina, restoring clearer vision. The epithelium is then allowed to re-grow naturally. This procedure does take longer to heal than the more widely used process of creating a flap that is opened allowing the laser to reshape the eye.

PRK is used to correct mild to moderate nearsightedness, in which the cornea of the eye is too steep.

Since it was first developed in 1987, more than a million PRK procedures have been performed. PRK used to be the most common laser vision correction procedure. LASIK has since surpassed PRK due to its ability to correct more severe visual acuity with less recovery time and with decreased risks of infection, haze and scarring.