TransPRK Xtra is a TransPRK procedure enhanced with an additional corneal strengthening procedure called Corneal Collagen Crosslinking. During TransPRK, the excimer laser thins the cornea in order to correct refractive errors like myopia and astigmatism. Therefore, higher degrees of spectacle power correction result in thinner corneas. Rarely, these thinner corneas may progressively bulge forward in a rare condition called Corneal Ectasia. TransPRK Xtra is postulated to reduce this risk by strengthening the cornea after it is thinned. The use of TransPRK Xtra is less frequently indicated because TransPRK saves corneal tissue by not requiring a flap to be created. This saves at least one-fifth of the corneal thickness compared to LASIK.