Photorefractive keratectomy, or PRK, is very similar to LASIK. Both are laser-assisted refractive procedures that ablate (vaporize with a laser) cells on the cornea. The major difference is that PRK reshapes the outermost surface of the cornea, whereas LASIK creates a corneal flap and treats the layer of tissue beneath the flap.
LASIK is generally preferred over PRK by ophthalmologists, because LASIK has a shorter recovery time and is generally more comfortable for the patient. Vision is slightly blurred for a short time after PRK, which gradually improves within 1-2 weeks. Your ophthalmologist may recommend PRK for you if you are not a LASIK candidate. The most common reason for denied LASIK candidacy is poor corneal thickness, as inadequate corneal thickness can lead to complications when creating a corneal flap.
Ultimately, patients should achieve the same visual outcome with either LASIK or PRK, but PRK will require slightly longer, more restrictive recovery.