Much of ophthalmic consultations are due to refraction problems. Most refractive errors are not diseases themselves, are small variations in the size or shape of the eyes that cause images to be blurred and we are forced to wear glasses, we speak of defects or errors ocular refraction: myopia, hyperopia or astigmatism. Laser techniques, performed on the anterior surface of the eye, the cornea, are the most used in myopia, hyperopia and astigmatism are not too high. The laser refractive surgery used, because of its proven safety and efficacy, is the technique known as LASIK. It consists in modifying the shape of the cornea to change the refraction or total ranking of the eye.