Photorefractive Keratectomy (PRK)
What is PRK?
Photorefractive Keratectomy, or PRK, is designed to correct nearsightedness (myopia), farsightedness (hyperopia), and astigmatism by using an excimer laser to reshape the cornea without creating a flap in the cornea.
PRK is an outpatient surgery and takes approximately 5-15 minutes per eye to complete. Although some pressure sensation may be felt during PRK, the procedure is generally painless. Before the procedure, anesthetic drops are used to numb the eye. During the procedure, an instrument holds the eyelid open and the patient is asked to focus on a target light. The surgeon then removes the surface layer of the cornea (the corneal epithelium) and uses an excimer laser to apply computer-controlled pulses of light energy to reshape the cornea.
After PRK is completed, the surgeon inserts a bandage contact lens to protect the cornea as the epithelial layer grows back over the next 3-4 days. This also helps decrease the discomfort experienced during this time, which is generally mild to moderate and can give the sensation that a foreign body is in the eye. Patients usually experience tearing, sensitivity to light, and a moderate amount of blurred vision which may prevent driving during the first 3 days. These phenomena are typically worst on the second and third days after the procedure, but improve greatly by the fourth and fifth days as the surface layer of the cornea grows back. During this time, chilled lubricating and medicated drops are prescribed to help to decrease discomfort, heal the cornea, and decrease the risk of scar formation and infection. The cornea heals from the edges towards the center, forming a “ridge” of epithelium across the pupil where the healing tissues meet. This ridge usually has formed by the fourth or fifth day, and it is safe to remove the bandage contact lens.
The vision is much improved by this time, generally ranging between 20/30 and 20/50, depending on the magnitude of the corrective treatment done. As the ridge of epithelium smoothes out over the next 4-6 weeks, the vision will gradually improve. The correction is usually considered to be stable by 3-6 months after surgery, at which time an enhancement could be considered if necessary.