LASIK is the most commonly performed laser eye surgery to treat myopia (nearsightedness), hyperopia (farsightedness) and astigmatism. The word "LASIK" is an acronym for "laser-assisted in situ keratomileusis."
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. LASIK surgery is essentially pain-free and takes only about 15 minutes for both eyes. The results — improved vision without eyeglasses or contact lenses — begin immediately after the procedure and vision usually continues to improve and stabilize over a few days.
If you're not a good LASIK candidate, a number of other vision correction surgeries are available, such as PRK and LASEK laser eye surgery and phakic IOL surgery.
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How is LASIK surgery performed? First, your LASIK surgeon will create a very thin, superficial flap in your cornea with a small surgical tool called a microkeratome or with a femtosecond laser.
LASIK eye surgery: step-by-step
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. Excimer lasers create a cool ultraviolet light beam to remove ("ablate") microscopic amounts of tissue from the cornea to reshape it so light entering the eye focuses more accurately on the retina 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.
After the laser ablation reshapes the cornea, the flap is then laid back in place, covering the area where the corneal tissue was removed. The flap seals to the underlying cornea during the healing period following surgery. LASIK 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 tear film on the surface of your eyes also will be evaluated, and a precautionary treatment may be recommended to reduce your risk of developing dry eyes after LASIK. Usually, an automated instrument called 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 also will ask you about 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. This is because contact lens wear can temporarily alter the natural shape of your cornea.
What to expect during LASIK
Before your LASIK surgery begins, numbing eye drops are applied to your eye to prevent any discomfort during the procedure. Your doctor may also give you some medication to help you relax. Your eye will be positioned under the laser, and an instrument called a lid speculum is used to keep your eyelids wide 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. After the corneal flap is created, 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 your surgeon 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
Upon completion of your LASIK procedure, your surgeon will have you rest for a bit. You may feel a temporary burning or itching sensation immediately following the procedure. After a brief post-operative exam, someone can drive you home. (You cannot drive after LASIK until your eye doctor sees you the following day and confirms your uncorrected vision meets the legal standard for driving.) 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 some doctors advise at least one day 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, your visual acuity will be measured to make sure it is safe for you to drive without glasses or contact lenses. In most states, this requires visual acuity of 20/40 or better.
As with any other surgery, it's very important for you to follow your doctor's instructions and take any medication prescribed. Also, avoid rubbing your eyes, as there's a small chance you could dislodge the corneal flap if you rub your eyes vigorously before the flap has securely reattached to the underlying cornea stroma.
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. If you have mild residual refractive error after LASIK and you want sharper vision for certain activities like driving at night, prescription lenses with anti-reflective coating often can be helpful.
Also, if you are sensitive to sunlight after LASIK, eyeglasses with photochromic lenses can reduce photophobia for clearer, more comfortable vision. While LASIK has an excellent safety profile, LASIK complications can occur. These include infection and night glare (from starbursts or halos appearing around lights).
A small percentage of people will need a LASIK enhancement, or "touch up" procedure, a few months after the primary LASIK surgery to achieve acceptable visual acuity. 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 with your eye doctor or surgeon any concerns you may have before you consent to having the surgery.