Laser surgery. Dummy's head demonstrating the use of an ultraviolet laser on the cornea structure at the front of the eye to surgically treat near- sightedness (myopia). After this photorefractive keratectomy (PRK) treatment, a patient does not require corrective spectacles. The single laser beam cuts away (excises) tissue in the patient's cornea to change its shape. This affects the way that light rays are bent as they pass through the cornea. Myopia is a condition where the eye is not focusing light properly, and in some cases is caused by asymmetries in the shape of the eye. Laser surgery may also be used to treat cases of longsightedness (hyperopia) or astigmatism.