 At baseline, before treatment, each eye is evaluated with autorefractometer measurement, best spectacle-corrected LogMAR visual acuity, Pentacam Scheimpflug photography, Goldmann applanation tonometry and biomicroscopy. The corneal biomechanical characteristics are assessed with applanation resonance tonometry and the ocular response analyzer. The investigations are repeated at 1 month, 6 months, 2 years and 5 years after the treatment. 