The excimer laser produces a high-energy, cold, ultraviolet light beam in pulses and delivers the pulses to a surface of the eye’s cornea. These pulses break the bond between molecules and tissue cells so that a controlled amount of tissue can literally be vaporized away to reshape the cornea—one microscopic layer at a time. The excimer laser is computer-controlled and programmed to custom treat each individual eye with a high degree of precision. For most cases, the thickness of the layer removed by the laser is less than the thickness of a human hair.