The excimer laser produces a high-energy, cool 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.

With some lasers, e.g. the WaveLight system from Germany, it only takes 5-10 seconds to complete the entire laser process to correct most levels of glasses or contact lens prescription.

You can see above and below to the right just how precise and gentle the excimer laser can be. Above a human hair has been etched into precise grooves. Below even words have been carved into the hair!

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. The laser only needs to remove 13 thousandths of a millimeter to correct one unit of glasses strength (dioptre)!