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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.
See also: Corneal surgery
Laser-Assisted In Situ Keratomileusis; Laser vision correction
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).
Why the Procedure Is Performed
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.
- You should be at least 18 years old (21 in some cases, depending on the laser used), because vision continues to change in people younger than 18. A rare exception is a child with one very nearsighted and one normal eye. Using LASIK to correct a very nearsighted eye may prevent amblyopia (lazy eye).
- You should not have this procedure if you are pregnant or breast-feeding, because these conditions can affect eye measurements.
- You should not have this procedure if you take certain prescription drugs, such as Accutane, Cardarone, Imitrex, or oral prednisone.
- Your eyes must be healthy and your prescription stable. If you are nearsighted, you should postpone LASIK until your condition has stabilized. Nearsightedness may continue to increase in some patients until their mid to late 20s.
- You should be in good general health. LASIK may not be recommended for patients with diabetes, rheumatoid arthritis, lupus, glaucoma, herpes infections of the eye, or cataracts. You should discuss this with your surgeon.
- Weigh the risks and rewards. If you're happy wearing contacts or glasses, you may not want to have the surgery.
- Make sure you have realistic expectations from the surgery.
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.
A small percentage of people may need to have another surgery because the condition is over- or under-corrected. Sometimes, you will still need to wear contact lenses or glasses.
Risks may include:
- Corneal infection
- Corneal scarring or permanent problems with the cornea's shape, making it impossible to wear contact lenses
- Decrease in contrast sensitivity -- even with 20/20 vision, objects may appear fuzzy or gray
- Dry eyes
- Glare or haloes
- Light sensitivity
- Night driving problems
- Patches of red or pink in the white of the eye (usually temporary)
- Reduced vision or permanent vision loss
Before the Procedure
A complete eye examination will be done before surgery to make sure your eyes are healthy. Other tests will be done to measure the curvature of the cornea, the size of the pupils in light and dark, the eyes' refractive error (to make sure LASIK is an option), and the thickness of the cornea (to make sure you will have enough corneal tissue left after surgery).
A signed informed consent form is needed before the procedure. This form confirms that you know the procedure's risks, benefits, alternative options, and possible complications.
After the Procedure
Immediately following the surgery, you may have burning, itching, or a feeling that something is in the eye. This usually doesn't last for more than 6 hours.
The doctor may prescribe a mild pain reliever medication. It is very important NOT to rub the eye after LASIK, so that the flap does not dislodge or move.
The day of surgery, vision generally is blurry or hazy, but by the next day the blurriness improves. Call the doctor immediately if you have severe pain or any of the symptoms worsen before your scheduled follow-up appointment (24 - 48 hours after surgery).
At the first doctor visit after the surgery, the eye shield will be removed and the doctor will examine your eye and test your vision. You may receive eye drops to help prevent infection and inflammation. Do not drive until your vision has improved enough to safely do so.
Other things to avoid include swimming, hot tubs, whirlpools, contact sports, lotions, creams, and eye makeup for 2 - 4 weeks after surgery. The doctor will give you specific instructions.
Most people's vision will stabilize in a few days after surgery, but for some people it may take up to 3 - 6 months.
Some people need an additional surgery to get the best possible results. Although a second surgery may improve distance vision, it may not relieve other symptoms such as glare, haloes, or problems with night driving. These are commonly reported complaints after LASIK surgery, especially when it is done using older methods. Often, these problems will go away by 6 months after the surgery, but a small number of people may continue to have problems with glare.
If your distance vision has been corrected with LASIK, it is likely that you will still need reading glasses at around age 45.
LASIK has commonly been performed in the United States since 1996. Most people seem to have stable and lasting vision improvement.
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. Preferred Practice Pattern Guidelines. Refractive Errors & Refractive Surgery. 2007. Accessed May 2, 2010.
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Review Date: 5/24/2010
Review By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant STudies, University of Washington, School of Medicine; and Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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