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The LASIK Procedure:
A Complete Guide

By Brian S. Boxer Wachler, MD

LASIK, or "laser-assisted in situ keratomileusis," is the most commonly performed laser eye surgery to treat myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.

Like other types of refractive surgery, the LASIK procedure reshapes the cornea to enable light entering the eye to be properly focused onto the retina for clearer vision.

Want a visual? View our LASIK slide show!

In most cases, laser eye surgery is pain-free and completed within 15 minutes for both eyes. The results — improved vision without eyeglasses or contact lenses — can usually be seen in as little as 24 hours.

A number of vision correction surgeries are available, such as PRK and LASEK laser eye surgery and phakic IOL surgery.

Your eye doctor will determine if laser eye surgery is suitable for your condition and, if so, which technique is best.

How is LASIK Surgery Performed?

First, your eye surgeon uses either a mechanical surgical tool called a microkeratome or a femtosecond laser to create a thin, circular "flap" in the cornea.

The surgeon then folds back the hinged flap to access the underlying cornea (called the stroma) and removes some corneal tissue using an excimer laser.

This highly specialized laser uses a cool ultraviolet light beam to remove ("ablate") microscopic amounts of tissue from the cornea to reshape it, refocusing light entering the eye for improved vision.

For nearsighted people, the goal is to flatten the cornea; with farsighted people, a steeper cornea is desired.

Excimer lasers also can correct astigmatism by smoothing an irregular cornea into a more normal shape. It is a misconception that LASIK cannot treat astigmatism.

After the laser reshapes the cornea, the flap is then laid back in place, covering the area where the corneal tissue was removed. Then the cornea is allowed to heal naturally.

Laser eye surgery requires only topical anesthetic drops, and no bandages or stitches are required.

Before LASIK Surgery

Your eye doctor will perform a thorough eye exam to ensure your eyes are healthy enough for the procedure. He or she will evaluate: the shape and thickness of your cornea; pupil size; refractive errors (myopia, hyperopia and astigmatism); as well as any other eye conditions.

The moistness of your eyes will also be evaluated, and a precautionary treatment may be recommended to reduce your risk of developing dry eyes after LASIK.

Usually, a corneal topographer is used to measure the curvature of the front surface of your eye and create a "map" of your cornea.

With wavefront technology associated with custom LASIK, you also are likely to undergo a wavefront analysis that sends light waves through the eye to provide an even more precise map of aberrations affecting your vision.

Your eye doctor will also note your general health history and any medications you are taking to determine if you are a suitable candidate for LASIK.

You should stop wearing contact lenses for a period of time advised by your doctor (typically around two weeks) before your eye exam and before the LASIK procedure, as contacts can alter the natural shape of your cornea.

How LASIK Works

Before your surgery begins, numbing eye drops are applied to your eye to alleviate any discomfort during the procedure. Your doctor may also give you some medication to help you relax.

An ultra-thin flap is created on the eye's surface during LASIK. After laser energy is applied to reshape the eye, the flap is replaced, to serve as a type of natural bandage.

Your eye will be positioned under the laser, and an instrument called a lid speculum is used to keep your eyelids open.

The surgeon uses an ink marker to mark the cornea before creating the flap. A suction ring is applied to the front of your eye to prevent eye movements or loss of contact that could affect flap quality.

The surgeon then uses a computer to adjust the excimer laser for your particular prescription.

You will be asked to look at a target light for a short time while he or she watches your eye through a microscope as the laser sends pulses of light to your cornea.

The laser light pulses painlessly reshape the cornea, although you may feel some pressure on your eye. You'll also hear a steady clicking sound while the laser is operating.

LASIK is performed on each eye separately, with each procedure taking only about five minutes.

Immediately After LASIK Surgery

Your doctor will have you rest for a bit, and typically you can return home right away (you will need someone to drive you). You may feel a temporary burning or itching sensation in your eyes immediately after surgery.

You should expect some blurry vision and haziness immediately after surgery; however, clarity should improve by the very next morning.

Your eyesight should stabilize and continue to improve within a few days, although in rare cases it may take several weeks or longer. For most people, vision improves immediately.

You may be able to go to work the next day, but many doctors advise a couple of days of rest instead.

Also, it is usually recommended that you refrain from any strenuous exercise for at least a week, since this can traumatize the eye and affect healing.

Generally, you will return to see your eye doctor or your LASIK surgeon the day after surgery.

At this initial check-up, he or she will test your vision to make sure you are legal to drive without glasses or contact lenses. In most states, this requires uncorrected visual acuity of 20/40 or better.

As with any other surgery, always follow your doctor's instructions, and take any medication prescribed. It also is important to refrain from rubbing your eye, as there is a small chance of dislodging the corneal flap.

Long-Term Results

Laser eye surgery offers numerous benefits and can dramatically improve your quality of life. Most people achieve 20/20 vision or better after the surgery, but LASIK results do vary. Some people may achieve only 20/40 vision or less.

You may still need to wear glasses or contact lenses following laser vision correction, though your prescription level typically will be much lower than before.

While the procedure has an excellent safety profile, post-operative LASIK complications can occur and may include infection or night glare (starbursts or halos that are most noticeable when you're viewing lights at night, such as while you're driving).

A small percentage of people have an enhancement, or "touch up," LASIK procedure for further improvement in vision.

You also may still need reading glasses once you reach your 40s, due to a normal age-related loss of near vision called presbyopia.

While LASIK surgery has a high success rate, it is important that you discuss all facets of the procedure with your surgeon prior to consenting to the surgery.

Additional Resources

To find an eye care practitioner in your area who specializes in LASIK eye surgery, visit our LASIK Surgeon Directory.

[Page updated May 2013]