PRK or photorefractive keratectomy) is a type of refractive surgery to correct myopia, hyperopia, and astigmatism. PRK was the first type of laser eye surgery for vision correction and is the predecessor of the popular LASIK procedure. Though PRK recovery takes a bit longer than recovery from LASIK eye surgery. PRK is still commonly performed and offers other advantages over LASIK for some of the patients. Like LASIK type of laser eye surgery, the PRK method also works by reshaping the cornea using an excimer laser, allowing light entering the eye to be properly focused on the retina for clear vision.
In LASIK a thin flap is created on the cornea with a microkeratome or a femtosecond laser. This flap is lifted above to expose the underlying corneal tissue with an excimer laser.
Whereas in PRK the thin outer layer of corneal epithelium is removed and discarded prior to reshaping the underlying corneal tissue with the excimer laser. The epithelium repairs itself within few days after the surgery.
The final results of PRK surgery are comparable to LASIK outcome but initial PRK recovery is generally slower because it takes few days for new epithelial cells to regenerate and cover the surface of the eye. Also, there is slightly increased risk of eye infection and haziness of the vision in the first few days after surgery. LASIK patients generally have less discomfort and their stabilization of the vision is also quicker, whereas the vision improvement with PRK it is slow and the actual outcome can take several weeks.
PRK, however, offers some distinct benefits. Because PRK surgery does not create a corneal flap which consists of both the epithelial and the stromal tissue, the entire thickness of the underlying stroma is available for the treatment. This is of particular benefit if the corneal is too thin for LASIK or if you have undergone LASIK previously and therefore have a thinner residual of the cornea. There is no complication of the risk of removing too much of the cornea with the excimer laser is reduced.
- Less depth of laser treatment than LASIK
- Suitable for patients with a thin cornea
- No risk of corneal flap complications
- Reduced risk of compromised corneal thickness
- Slower recover than LASIK
- Better vision takes longer to obtain
- Increased risk of post-surgery infection, inflammation, and haze
- More eye discomfort during early PRK recovery, compared with recovery after LASIK surgery.