In ophthalmology, laser treatment is primarily associated with refractive surgery, mostly LASIK. This is a corneal surgical method for restoring optimum vision without corrective lenses. The LASIK method involves the detachment of a thin flap from one side of the cornea using a Femtolaser. The flap is then folded back, although it remains attached to the cornea. The precise laser correction is then performed on the underlying cornea. In cases of myopia, tissue is extracted from the middle of the cornea. In cases of hyperopia, the tissue is taken from a ring surrounding the middle of the cornea. The flap is restored to its original position after conclusion of the ablative process. LASIK allows corrections of up to -8 diopter in cases of myopia and up to +5 diopter in hyperopia cases, provided the cornea is thick enough.