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PRK Photo-Refractive Keratectomy

Most of us have now heard about LASIK, laser-assisted intra-stromal keratomeliusis. This refractive procedure has become the standard for vision correction over the past years. In order to meet some of the limitations of LASIK and to improve upon its safety, an alternative to LASIK is called PRK.

Photo-Refractive Keratectomy became possible when scientists discovered that a special ultraviolet light called excimer laser could remove precise amounts of tissue without damage to the surrounding structures. In applying this unique capability to the eye, surgeons found that the cornea could be treated, improving the focus of an image on the retina, the layer in the back of the eye that acts like film in a camera. Widespread clinical studies over a five-year period established that this treatment is safe and effective with permanent and stable benefits to vision. To date a large number of procedures have been performed around the world, validating the long-term safety and stability by a successful track record in Europe that extends nearly 10 years. PRK is accomplished by removing the surface layer of cells from the anesthetized cornea, applying the laser energy over a 8-35 second period to flatten the cornea to a pre-calculated degree, and placing a contact lens on the healing area for about 3 days. Functional vision return takes 3-5 days typically, while the surface layer restores itself.

PRK overcomes flap-related issues by eliminating this aspect from the procedure. The surgeon merely removes the epithelial layer completely. Then the surgeon works just below the cell layer utilizing the full thickness of the cornea’s collagen. There is no flap to subtract from the available tissue for the reshaping process. After the laser treatment, new cells will fill in and reform this layer over a span of 3-5 days. More gradual recovery of clear vision and 24-36 hours of using drops to reduce eye discomfort. A small percentage of cases developed hazing of the cornea that took some time to resolve. Eye drop use is more prolonged after PRK.

With PRK the eye benefits from the fact that a thicker cornea is more stable after laser treatment, dry eye is less severe or absent, there are no flap complications to manage, and results to date have shown vision quality is superior to LASIK long term. There remains a small risk of corneal haze. Haze appears to clear over time in virtually all cases.