PRK (Photorefractive Keratectomy) is largely the same as LASIK, but here there is no flap cut before the laser surgery is applied.  The epithelium is removed manually, or alcohol assisted, and then the laser surgery is done directly on the superficial tissue of the cornea.  

Because the epithelium is removed, there is considerable discomfort post-operatively.  Recovery time is usually about a month until vision returns to the best possible amount.  This procedure however is slightly safer than LASIK because of the lack of a flap.  The depth at which tissue is altered in the cornea is less than in LASIK, making the risk for ectasia less.  Haze is also a possible complication, but many studies prove that the modern techniques used has largely removed this complication.


With Trans-PRK (Transepithelial Photorefractive Keratectomy) the epithelium is removed with the laser, then the laser is applied to the superficial layers of the cornea exactly as in a PRK.  The major difference with the Schwind Amaris laser is that because of the SmartSurfACE technology, the surface is smoother and therefore recovery is much quicker than with other systems. 

Recovery time is about a week, as a much smaller area of epithelium is removed.  It is the most versatile procedure as all patients that qualify for any other procedure, will qualify for a TransPRK, but not vice-versa.