Photorefractive keratectomy (PRK) is a type of refractive eye surgery that uses an excimer laser to reshape the cornea, improving vision by correcting refractive errors such as myopia, hyperopia, and astigmatism. PRK involves removing the outer layer of the cornea (epithelium) and then using the laser to ablate the underlying corneal tissue, allowing for more accurate focusing of light onto the retina.