PRK is an acronym, which stands for photorefractive keratectomy, which is similar to LASIK. The major difference is that instead of creating a corneal flap as in LASIK, in PRK the corneal surface cells are removed first, and the excimer laser (identical to that used in LASIK) is used to treat the corneal surface directly without creating a flap first. The long-term outcomes are the same between LASIK and PRK. However, PRK patients recover more slowly because it takes about five to seven days for corneal surface to heal after the laser treatment. Immediately after PRK, patient wears a bandage contact lens in the treated eye to relieve discomfort and to accelerate recovery. Improvement in vision also takes longer in PRK patients. It may take a few weeks for patient to achieve optimal vision. There is a slightly higher risk of develop haziness in cornea with PRK. PRK is usually reserved for patients whose corneas are too thin to undergo LASIK or for patients who had LASIK before and need enhancement to correct residual refractive error.