With PRK, the excimer laser is applied directly to the surface of the cornea to reshape it, correcting nearsightedness, farsightedness and astigmatism and focusing the image directly on the retina. With PRK, we can correct thinner corneas and those with certain conditions requiring treatment of the superficial corneal layers.  PRK is less invasive than LASIK or IntraLASIK because with LASIK a flap is made in the cornea. With PRK, the correction is made on the surface of the cornea without the need to create a flap.