| How Laser Eye Surgery Works |
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Last week, the Carl Zeiss company from Germany, announced the FDA accredition of their newest Excimer laser, the MEL 80™. Since Laser Eye Surgery such as Lasik gets more and more popular, it's time to have a closer look on how Laser Surgery works. The Technology of Laser SurgeryRefraktive laser surgery is always accomplished with a Excimer laser. The invention of the Excimer laser by IBM made the laser surgery possible. Excimer laser (the name derives from “excited” and “dimer”) uses reacting gases, like chlorine and fluorine, mixed with inert gases such as argon, krypton or xenon. If this gas mixture is electrically stimulated, a pseudo molecule (dimer) is produced, that emits light within the ultraviolet range. The Excimer laser is a cool laser; that means that it does not heat the surrounding air or the surfaces. Instead a tightly focused ultraviolet light beam is emitted. The ultraviolet light is absorbed by the upper layer of the surface. The strength of the ultraviolet laser beam breaks down most organic bonds, so the material (like the cornea of the eye) vanishes. The ultraviolet laser penetrates less than a nanometer (a billionth of a meter) into the surface the cornea. The heat, which is caused by the energy of the laser, is dissipated together with this microscopic layer of the cornea. This process is called photoablation.Laser corrections of defective visions with the Excimer laser are extraordinarily effective and patient friendly. The technology uses a very small laserspot with Gauss jet profile. Thus the cornea can be eroded particularly evenly. The surrounding fabric is preserved under this treatment. The necessary erosion of the cornea takes place very fast, what leads to a decreased dehydrogenation of the eye during the operation. The distribution of the laser beam is optimized, thus the remaining stromale fabric is protected thermally despite the high ablation speed. Since the patient must concentrate only for few seconds on the fixing light, the strain for the patient decreases considerably. Results of the Laser TreatmentThe results of the clinical studies show that 93% of the treated patients gained a visus of 1.0 or better after three months. A visus of 1.0 corresponds to a visual acuity of 100%. After six months the visus for 41% of the treated patients reached 1.6 or above. In addition the results showed that 85% of the patients during a re-examination after three months had a refraction with a deviation smaller than a half diopter to the desired goal value. |
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