PRK (Photorefractive keratectomy)
Photorefractive keratectomy (PRK) is a laser vision correction procedure that uses an excimer laser, the same type of laser used in LASIK, to remove a small amount of the cornea in order to correct vision. PRK is often used for patients whose eye structure isn’t suitable for the LASIK procedure. This includes patients with larger pupils and those with thin corneas.
About the Procedure
The topography-guided PRK procedure is very similar to LASIK, taking only a few minutes to perform and completely customized to each patients’ eyes to achieve their best personal vision.
The main difference is that unlike LASIK, in which a corneal flap is created and then put back in place after the corneal tissue underneath is reshaped, in PRK, the thin outer layer of the cornea, the epithelium, is completely removed before reshaping the underlying corneal tissue with the laser. The epithelium repairs itself by growing back over the corneal surface within a few days after surgery.
A clear contact lens is placed on the eye at the end of surgery as a “bandage” to reduce irritation during the healing process and to protect your eye. After the epithelium is allowed to grow back, your ophthalmologist will remove the contact lens at a follow-up appointment.
The final results of PRK are comparable to LASIK, although the initial recovery is slower because it takes a few days for new epithelial cells to regenerate and cover the surface of the eye. Those who opt for PRK can expect hazy vision for a few days after surgery as the eye heals and a more gradual improvement in vision, which can take several weeks to fully stabilize.
Differences of PRK Compared to LASIK
- Mild discomfort, including eye irritation and watering, that may last several days following the procedure. This is due to the corneal surface cells (epithelium) regenerating.
- Longer time to reach stable vision. Typically, vision is about 80% improved a month after surgery and about 95% improved 3 months after surgery. LASIK, in contrast, provides a more rapid visual recovery.
- When both eyes are treated, many patients take off work for up to one week to allow the irritation and vision to improve to a more acceptable level, whereas LASIK patients can return to their normal routine within a couple of days of their procedure.
Although PRK has a longer recovery time and more discomfort during the healing than LASIK, the main advantage of the procedure is that it offers vision correction for those who are not able to undergo LASIK.
Another chance to achieve visual freedom even if you’re not a candidate for LASIK
Combination PRK/Cross-linking for Corneal Ectasia
Post-LASIK corneal ectasia is a rare condition similar to keratoconus that can sometimes develop after a LASIK surgery in which the cornea begins to thin and bulge forward, slowly worsening vision.
For those who develop post-LASIK corneal ectasia, your ophthalmologist may recommend a combination PRK and cross-linking procedure to improve your vision and strengthen the weakened cornea.
A PRK procedure is preferred to LASIK for those with corneal ectasia, as it removes a thinner layer of the cornea. During the PRK procedure, your doctor will also place riboflavin (vitamin B-12) eye drops on the cornea and shine a specific type of ultraviolet light onto the cornea. This corneal cross-linking procedure causes new corneal collagen cross-links to develop, leading to a stiffer, stronger cornea.