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A type of refractive surgery of the cornea to correct myopia and astigmatism, using an excimer laser. An excimer laser is a laser containing a noble gas, such as helium or neon, which is based on a transition between an excited state in which a metastable bond exists between two gas atoms and a rapidly dissociating ground state. The extremely precise laser light reshapes the surface of the cornea without making an incision. This procedure can reduce much higher degrees of myopia than radial keratotomy (KERATOTOMY, RADIAL), although it generally takes longer for vision to clear. (From In Focus 1994;1 (2):3 and McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p675)