PRK is an outpatient procedure, done under topical anesthetic eye drops. It takes about fifteen minutes. The epithelium, the outer cell layer of the cornea, is removed with a blade, alcohol or a laser. An excimer laser, which produces ultraviolet light and emits high-energy pulses, is used to remove a thin layer of corneal tissue. The laser beam vaporizes the surface of the cornea up to that precise depth. By breaking the bonds that hold the tissue molecules together, your cornea is reshaped, correcting the refractive error. Because no incisions are made, the procedure does not weaken the structure of the cornea.
More recent variations of PRK include procedures which replace the corneal epithelium after removing it with alcohol (LASEK) or an instrument with a blade similar to the microkeratomes sometimes used for LASIK (Epi-LASIK). Collectively, all of these procedures are considered variations of surface ablation of the cornea, and in the literature any of them may be referred to as “advanced surface ablation”. All of these are essentially the same procedure and yield the same visual results.
Immediately following surgery a bandage contact lens is placed on the eye, Vision is blurry for 3 days to one week. It may take a month or longer to achieve one’s best vision. One eye can be done at a time so less downtime is needed.
Possible complications of PRK surgery include under correction, overcorrection, poor night vision and corneal scarring, although permanent vision loss is very rare. In the 1990′s, concern over corneal haze formation and loss of surgical refractive effect led surgeons to limit PRK surgeries to patients with nearsighted corrections of 6 Diopters or less, but newer laser technology and the use of small, one time doses of the anti-metabolite Mitomycin C during PRK surgery have greatly expanded the range of PRK, as haze formation is now exceedingly rare no matter what the correction.
Many patients enter the evaluation process for laser vision correction with the impression that visual results after PRK are not as good as LASIK. This was true for high levels of correction 10 years ago, but is no longer. Recent peer-reviewed publications of visual results after PRK report results at least equivalent to (and in some cases, better than) LASIK for comparable levels of refractive error.
To be a candidate for the procedure you must have a stable and appropriate refractive error, be free of eye disease, be at least 18 years old and be willing to accept the potential risks, complications and side effects of PRK. PRK is frequently recommended over LASIK for those patients who are at risk for eye trauma (active duty military personnel, certain athletes) or who have a corneal shape or thickness not appropriate for LASIK. Additionally, patients with very dry eyes, those who have a history of frequent corneal abrasions or who have had prior RK or other corneal surgery are often best suited for ASA rather than LASIK Surgery. Advanced Surface Ablation is therefore the safest form of Laser refractive surgery.