Laser eye surgery. Computer screen display used to monitor an ultraviolet laser during surgery on the cornea structure at the front of the eye. This is part of near-sightedness (myopia) treatment. After this photorefractive keratectomy (PRK) treatment, a patient does not require corrective spectacles. A laser beam cuts away 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 caused because 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 longsightedness (hyperopia) or astigmatism.