Laser-Assisted In Situ Keratomileusis; Laser vision correction
LASIK is eye surgery that permanently changes the shape of the cornea (the clear covering on the front of the eye) in order to improve vision and reduce a person's dependency on glasses or contact lenses.
For clear vision, the eye's cornea and lens must bend (refract) light rays properly, so that images are focused clearly on the retina. Otherwise, the images will be blurry.
This blurriness is referred to as a "refractive error." It is caused by a difference between the shape of the cornea (curvature) and the length of the eye. LASIK uses an excimer laser (an ultraviolet laser) to precisely remove corneal tissue, giving it a new shape so that light rays are focused clearly on the retina. LASIK causes the cornea to be thinner.
LASIK is an outpatient surgical procedure. It will take 10 to 15 minutes to perform for each eye.
The only anesthetic used is eye drops that numb the surface of the eye. The procedure is done when you are awake, but you will get medicine to help you relax. LASIK may be done on one or both eyes during the same session.
Originally during LASIK, a special automated knife (a microkeratome) was used to cut a hinged flap of corneal tissue from the outer layer of the eyeball. Now it has become common to use a different type of laser (femtosecond) to create the corneal flap. The flap is put aside and the excimer laser is used to reshape the corneal tissue underneath.
The amount of tissue the laser will remove is calculated ahead of time. Once the reshaping is done, the surgeon replaces and secures the flap. No stitches are needed. The cornea will naturally hold the flap in place.
An eye shield or patch will be placed over the eye to protect the flap and to help prevent rubbing or pressure on the eye until it has had enough time to heal (usually overnight).
LASIK is most often done on people who use glasses or contact lenses because of nearsightedness (myopia). It is occasionally used to correct farsightedness. It may also correct astigmatism.
The FDA and American Academy of Ophthalmology have developed guidelines and recommendations that indicate which people would be good candidates for LASIK.
For patients with presbyopia, it's important to note that LASIK cannot correct vision so that one eye can see at both distance and near. However, LASIK can be done to allow one eye to see near and the other far, which is called "monovision." If you can adjust to this correction, it may eliminate or reduce your need for reading glasses.
In some instances, surgery on only one eye is required. If your doctor thinks you're a candidate, ask about the pros and cons.
Wilkinson PS, Davis EA, Hardten DR. LASIK. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, Mo: Mosby Elsevier; 2008:chap 3.5.
American Academy of Ophthalmology Refractive Management/Intervention Panel.
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