| Excimer laser makes eye surgery safe |
| Written by James Black | |
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The Excimer laser is a powerful and incredibly accurate laser used for semi-conductor manufacturing and laser eye surgery. The importance of this laser to eye surgery cannot be understated because the properties of this remarkable device are what makes laser-assisted refractive surgery possible.
In laser-assisted refractive surgery, surgeons work to repair flaws in the curvature or the shape of the cornea in order to improve the patient's vision. When laser refractive surgery is performed, the surgeon either cuts a flap into the surface of the cornea, or weakens it in another way in order to gain access to the surface beneath. Once access is gained, the surgeon uses an Excimer laser to sculpt and mold the cornea into the proper shape that will allow the patient to see correctly. The unique properties of the Excimer laser -- the ability to sculpt the cornea without penetrating the eye and the lack of heat damage -- are what makes this surgery possible. To best understand the Excimer laser, an understanding of the history of lasers and how they work is important. The key principles of the mechanics of the laser were postulated in the late 1910's by Albert Einstein. Einstein laid out the general principles of how lasers would work, describing his theory of stimulated emmission, or how to agitate atoms to produce the radiation of light. Einstein's theories concerning stimulated emmission were first put to practical use in 1960 by Hughes Research Laboratories scientist Theodore Maiman, who developed the first working laser. Maiman's laser used a ruby crystal to produce a red light laser. Following Maiman's development, other breakthroughs in the field followed, such as Ali Javan's gas laser in 1960 and the invention of the laser diode in 1962. Lasers have been used in a number of practical applications in many fields, including home entertainment, medical diagnosis and imaging, industry and surgery. The Excimer laser was first developed in Moscow in 1970 by Lebedev Physical Institute researchers V.A. Danilychev and Yu. M. Popov. The Excimer laser uses an electron beam to excite an xenon dimer in order to produce stimulated emission. The original design was improved in 1975 by researchers at the U.S. Naval Research Laboratory, the Northrop Research and Technology Center and the Avco Everett Research Laborator to make use of noble gas halides. The Excimer laser is useful in medical applications because it does not burn or cut material, but instead it produces energy that disrupts the molecular bonds of organic tissue, causing them to disintergrate through a process known as abalation. Abalation is the removal of material from the surface of an object by vaporization, chipping or some other type of erosive process. The Excimer laser was not, at first used for medical applications. When first developed, the Excimer laser was used in the manufacture of semiconductor components. It wasn't until the early 80s that researchers observing the use of Excimer lasers on biological materials theorized that the laser could make the type of precise cuts needed for very delicate surgical operations, such as eye surgery. The first medical applications of the Excimer involved their use in angioplasty, or the widening of blocked or narrowed blood vessels. Researchers at Kansas State University pioneered the use of Excimer lasers in refractive eye surgery. The first laser-assisted refractive surgery was known as PRK. Eventually, the LASIK technique, which is the industry standard today, was developed in the early 90s. In LASIK, a surgeon uses a blade to cut a flap in the surface of the cornea. The Excimer laser is then used to mold and sculpt the cornea into the desired shape, which will improve the patient's vision. The standard Excimer laser costs about $50,000 to $200,000. The key advantages of Excimer lasers' use in eye surgery are their accuracy and their limited potential to cause damage to the eye. A key drawback of the Excimer laser's use in medical settings has been its bulky size. Newer Excimer models are getting progressively smaller, however, increasing convenience for doctors. Laser-assisted refractive surgery has proven to be very effective and safe, and offers the advantage of almost immediate results. Laser-assisted refractive surgery techniques are being continually refined, and new techniques such as LASEK and Epi-LASIK have been introduced in recent years. The Excimer laser remains an important component of these new techniques however. |
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