Abstract
The excimer laser allows the correction of myopic, hyperopic and astigmatic refractive errors by ablating the corneal surface. To get the best treatment and the best postoperative visual correction, it is necessary the proper maintenance and calibration of all laser parameters and environmental factors in the operating room. After surgery, in some situations, an increase in aberrations occurs, which greatly affect the patient’s visual quality. At present new devices have been introduced which are based on guided wavefront ablation and topographic ablation, with the aim of reducing postoperative aberrations. This paper examines the main parameters of excimer laser that influence ablation, like different profiles of corneal ablation, and demonstrates how they directly relate to postoperative visual quality.