By Mayo Clinic Staff
Laser-assisted in-situ keratomileusis (LASIK) eye surgery is a procedure that corrects certain vision problems, reducing or eliminating the need for eyeglasses or corrective lenses.
LASIK eye surgery is the most common type of refractive surgery. Refractive surgery changes the shape of the dome-shaped transparent tissue (cornea) at the front of your eye.
The desired result of LASIK eye surgery is to bend (refract) light rays to focus more precisely on your retina rather than at some point beyond or short of your retina.
The goal of LASIK eye surgery is to produce clearer, sharper vision.
LASIK eye surgery may be an option for you if you have one of these vision problems:
- Nearsightedness (myopia). When your eyeball is slightly longer than normal or when the cornea curves too sharply, light rays focus in front of the retina and blur distant vision. You can see objects that are close more clearly, but not those that are far away.
- Farsightedness (hyperopia). When you have a shorter than average eyeball or a cornea that is too flat, light focuses behind the retina instead of on it. This makes near vision and sometimes distant vision blurry.
- Astigmatism. When the cornea curves or flattens unevenly, the result is astigmatism, which disrupts focus of near and distant vision.
Your eye doctor will likely recommend that you try other ways of correcting your vision, such as by using glasses or contact lenses, before you turn to LASIK eye surgery or another similar refractive procedure.
As with any surgery, LASIK eye surgery carries risks, including:
Undercorrections. If the laser removes too little tissue from your eye, you won't get the clearer vision results you were hoping for. Undercorrections are more common for people who are nearsighted.
You may need another refractive surgery (enhancement surgery) within a year to remove more tissue.
- Overcorrections. It's also possible that the laser will remove too much tissue from your eye. Overcorrections may be more difficult to fix than undercorrections.
- Vision returning to pre-surgery vision. Over time, your eyes may slowly return to the level of vision you had before surgery. This may happen due to certain conditions, such as abnormal wound healing, hormonal imbalances or pregnancy.
- Visual loss or changes. Rarely, you may experience loss of vision due to surgical complications. Some people also may not see as sharply or clearly as previously.
- Astigmatism. Astigmatism can be caused by uneven tissue removal. It may require additional surgery, glasses or contact lenses.
Glare, halos and double vision. After surgery you may have difficulty seeing at night. You might notice glare, halos around bright lights or double vision.
Even when a good visual result is measured under standard testing conditions, your vision in dim light (such as at dusk or in fog) may be reduced to a greater degree after the surgery than before the surgery.
Dry eyes. LASIK causes a temporary decrease in tear production. For the first six months or so after your surgery, your eyes may feel unusually dry as they heal. Dry eyes can reduce the quality of your vision.
Your eye doctor might recommend that you use eyedrops during this time. If you experience severe dry eyes, you could opt for another procedure to get special plugs put in your tear ducts to prevent your tears from draining away from the surface of your eyes.
Flap problems. Folding back or removing the flap from the front of your eye during surgery can cause complications, including infections, excess tears and inflammation.
The outermost corneal tissue layer (epithelium) may grow abnormally underneath the flap during the healing process.
Conditions that increase risks
Certain health conditions can increase the risks associated with LASIK surgery or make the outcome less predictable. Doctors may not recommend laser surgery for you if you have certain conditions.
These conditions include:
- Autoimmune disorders, such as rheumatoid arthritis
- Immunodeficiency conditions caused by immunosuppressive medications or HIV
- Persistent dry eyes
- Unstable vision due to medications, hormonal changes, pregnancy, breast-feeding or age
- Several eye conditions, such as keratoconus, keratitis, uveitis, herpes simplex affecting the eye area, glaucoma, cataracts, eye injuries or lid disorders
LASIK may not be advisable if you:
- Have fairly good overall vision
- Have very large pupils or thin corneas
- Have a job that may be affected if you have the procedure
- Have age-related eye changes that cause you to have less clear vision (presbyopia)
- Participate in contact sports that may be associated with blows to the face
If you're considering LASIK eye surgery, talk to your doctor about your questions and concerns. He or she can explain how the surgery might benefit you and help put the risks in perspective. Your doctor will discuss with you whether you're a candidate for the procedure.
To prepare for LASIK eye surgery:
- Stop wearing your contact lenses. If you wear contact lenses, you'll need to switch to glasses full time for at least a few weeks before your surgery.
Contact lenses can distort the shape of your cornea, which could lead to inaccurate measurements and a poor surgical outcome. Your doctor will provide specific guidelines depending on your situation and how long you've been a contact lens wearer.
- Skip the eye makeup. Don't use eye makeup, cream, perfumes or lotions on the day before and the day of your surgery.
Your doctor may also instruct you to clean your eyelashes daily or more often in the days leading up to surgery, to remove debris and minimize your risk of infection.
- Arrange for a ride home. You'll need to have someone drive you to and from your place of surgery. Immediately after surgery, you might still feel the effects of medicine given to you before surgery, and your vision may be blurry.
- Know what surgery may cost you. LASIK eye surgery is usually considered elective surgery, so most insurance companies won't cover the cost of the surgery. Be prepared to pay out of pocket for your expenses.
LASIK eye surgery is performed using a laser programmed to remove a defined amount of tissue from your cornea. With each pulse of the laser beam, a tiny amount of corneal tissue is removed.
The laser allows your eye surgeon to flatten the curve of your cornea or make it steeper. Often, LASIK is performed on both eyes on the same day.
Before surgery, your doctor will discuss the risks and benefits of LASIK surgery, your expectations, what to expect before and after surgery, and answer any questions you may have.
During a pre-surgical eye exam, your eye doctor takes a detailed medical and surgical history and conducts a comprehensive eye examination.
In the eye examination, your doctor will evaluate your vision and look for signs of eye infections, inflammation, dry eyes, large eye pupils, high eye pressure or other eye conditions.
Your doctor will also measure your cornea, noting the shape, contour, thickness and any irregularities.
Your eye doctor also evaluates which areas of your cornea need reshaping. Your eye doctor uses tests to measure the shape and contour of your cornea and determine the precise amount of tissue to remove from your cornea.
Doctors generally use wavefront-guided technology to evaluate your eye in detail before LASIK surgery. In this test, a scanner creates a highly detailed chart, similar to a topographical map, of your eye. Theoretically, the more detailed the measurements, the more accurate your eye doctor can be in removing corneal tissue.
LASIK eye surgery is usually completed in 30 minutes or less. During the procedure, you lie on your back in a reclining chair. You may be given medicine to help you relax. After numbing drops are placed in your eye, your doctor uses an instrument to hold your eyelids open.
A suction ring placed on your eye just before cutting the corneal flap may cause a feeling of pressure, and your vision may dim a little.
Your eye surgeon uses a small blade or cutting laser to cut a hinged flap about the size of a contact lens away from the front of your eye. Folding back the flap allows your doctor to access the part of your cornea to be reshaped.
Using a laser, your eye surgeon then reshapes specific parts of your cornea. After reshaping is complete, the flap is folded back into place and usually heals without stitches.
During the surgery, you'll be asked to focus on a point of light. Staring at this light helps you keep your eye fixed while the laser reshapes your cornea.
You may detect a distinct odor as the laser removes your corneal tissue. Some people describe smelling an odor similar to that of burning hair.
If you need LASIK surgery in both eyes, doctors will generally conduct the procedure on the same day.
Immediately after surgery, your eye may itch, burn and be watery. You'll probably have blurred vision. You generally will experience little pain, and you'll usually recover your vision quickly.
You may be given pain medication or eyedrops to keep you comfortable for several hours after the procedure. Your eye doctor might also ask you to wear a shield over your eye at night until your eye heals.
You'll be able to see after surgery, but your vision won't be clear right away. It takes about two to three months after your surgery before your eye heals and your vision stabilizes. Your chances for improved vision are based, in part, on how good your vision was before surgery.
You'll have a follow-up appointment with your eye doctor one to two days after surgery for your doctor to see how your eye is healing and check for any complications.
Plan for other follow-up appointments during the first six months after surgery as your doctor recommends.
It may be a few weeks before you can start to use cosmetics around your eyes again. You might also have to wait several weeks before resuming strenuous contact sports, swimming or using hot tubs.
Follow your doctor's recommendations about how soon you can resume your normal activities.
Refractive surgery often offers improved vision without the hassle of glasses or contact lenses. In general, you have a very good chance of achieving 20/25 vision or better after refractive surgery.
More than 8 out of 10 people who've undergone refractive surgery no longer need to use their glasses or contact lenses for the majority of their activities.
Your results depend on your specific refractive error and other factors. People with a low grade of nearsightedness tend to have the most success with refractive surgery. People with a high degree of nearsightedness or farsightedness along with astigmatism have less predictable results.
Many people have positive results and report high satisfaction after LASIK surgery. However, long-term results often aren't available, as many people are sufficiently satisfied after surgery. They don't feel a need for repeat examination, and they become lost to follow-up. Also, the LASIK procedure has evolved over time, and the procedure done today is different from the procedure done a few years ago.
Feb. 25, 2014
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