To reduce a persons dependency on glasses or contact lenses one can have Lasik surgery. The term LASIK stands for Laser-Assisted In Situ Keratomileusis and is a procedure through which you permanently changes the shape of the cornea. The cornea is the clear covering of the front of the eye. Doctors use an excimer laser to perform this kind of surgery. A small knife, called a microkeratome, is used to cut a flap in the cornea. A hinge is left at one end of this flap. The flap is folded back revealing the stroma, the middle section of the cornea. The pulses from a computer controlled laser vaporize a portion of the stroma and the flap is replaced. Other techniques are also in use. The cornea is a part of the eye that helps focus light to create an image on the retina. The bending and focusing of light is also known as refraction. The shape of the cornea and the eye are usually not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called refractive errors. There are three primary types of refractive errors: myopia, hyperopia and astigmatism. Persons with myopia, or nearsightedness, have more difficulty seeing distant objects as clearly as near objects. Persons with hyperopia, or farsightedness, have more difficulty seeing near objects as clearly as distant objects. Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye. Combinations of myopia and astigmatism or hyperopia and astigmatism are common. Glasses or contact lenses are designed to compensate for the imperfections of the eye. Surgical procedures aimed at improving the focusing power of the eye are called refractive surgery. With Lasik surgery, precise and controlled removal of corneal tissue by a special laser reshapes the cornea and changes its focusing power. Before Lasik there were other techniques developed to reshape the cornea for example Photorefractive Keratectomy. Often the exact same laser is used for the two types of surgery. The major difference between the two surgeries is the way that the stroma, the middle layer of the cornea, is exposed before it is vaporized with the laser. In PRK, the top layer of the cornea, called the epithelium, is scraped away to expose the stromal layer underneath. In LASIK, a flap is cut in the stromal layer and the flap is folded back. Can anyone have a Lasik surgery? Most but not everyone and certain complications are unavoidable in a percentage of patients, and there are no long term data available for current procedures. Also, some jobs prohibit certain refractive procedures so be sure to check with your employer/professional society/military service before undergoing any procedure. Most medical insurance will not pay for refractive surgery and the cost is still significant. If you have what is called refractive instability, like young people, you can not have this kind of surgery. If you are pregnant or have certain diseases like diabetes or are taking medications you should not have Lasik surgery. In these cases you should discuss the possible additional risks with your doctor.
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