Photorefractive kertectomy (PRK)
PRK Surgery :
PRK surgery, or PhotoRefractive Keratectomy, is a type of laser surgery to correct moderate nearsightedness, farsightedness and astigmatism. PRK surgery reshapes the cornea with a laser so that light is more effectively focused on the retina to improve vision.
How is PRK Surgery carried out?
PRK surgery, unlike LASIK eye surgery, does not use a knife or cutting laser to create a flap in the cornea. Instead, PRK surgery removes a thin layer (Epithelium) of the cornea’s surface and reshapes the surface of the cornea to correct the vision.
Pros & Cons:
This was the most popular laser procedure for correcting refractive errors before the advent of LASIK. Since the epithelium (surface layer of the cornea) is removed, this leads to greater activation of inflammatory mediators and better healing. The problems of excessive healing or haze (scar) can decrease the clarity of vision, and regression or refractive error returning due to the addition of tissue. Haze and regressions are more if the error is high. Generally PRK is recommended for cases up to 6.0 diopters.
The problems encountered in the early post-operative period with PRK are more painful (because of epithelial defects) and delay visual rehabilitation as it takes 3-4 days for the epithelium to heal.
Early visual recovery, more comfort, practically no haze and very little regression (not in all cases) are the advantage of LASIK over PRK. PRK is preferred in cases with borderline corneal thickness where LASIK might be risky.