Introduced in the early 1990s, LASIK is currently the most popular surgical procedure used to correct nearsightedness, farsightedness and astigmatism. 

LASIK can also correct presbyopia, but only via monovision (one eye corrected for clear distance vision, and the other eye corrected for clear near vision).   

The word LASIK is an acronym for LASer In-situ Keratomileusus, which means, "to reshape the cornea with a laser." 

The LASIK procedure involves the use of a special type of laser called the Excimer laser.  Originally developed by IBM to etch computer chips, the Excimer laser creates a "cool" beam of ultraviolet light, meaning that most of the heat it generates dissipates quickly into the air.  This makes the Excimer laser ideal for eye surgery because it can vaporize (ablate) corneal tissue without causing thermal damage to surrounding tissue.

The Excimer laser is also extremely precise.  It can remove corneal tissue with an accuracy of 0.25 microns (less than one one-thousandth of a millimeter).  For most LASIK procedures, the proper vision correction can be achieved by removing only about 50 microns of corneal thickness.  This is approximately the thickness of a single human hair.

How is LASIK performed?

The steps in the LASIK procedure are as follows:

1.      Detailed measurements of the eye are performed to determine the exact amount of cornea to be removed.

2.      Anesthetic eye drops are applied to numb the eye.

3.      A speculum device is applied to the eyelids to hold them open during the surgery.

4.      An instrument called a microkeratome is used to cut a small flap of corneal tissue.  The flap remains attached to the cornea on one side.

5.      The flap is folded back to expose the central corneal tissue.

6.      The excimer laser delivers a programmed number of pulses of ultraviolet light to the exposed cornea.  Each pulse removes a microscopic amount of corneal tissue, thereby changing the shape of the front of the eye.

7.      After the laser treatment is completed, the corneal flap is folded back to its original position.  There is no need for stitches to keep the flap in position.

With the cornea now reshaped, light focuses more directly on the retina for clearer eyesight.
 

The entire LASIK procedure for both eyes usually takes less than 15 minutes.

What to expect immediately after LASIK

The day you have LASIK performed, you will be given detailed instructions on what to do and not do as your eyes recover from the LASIK procedure.  These instructions may include the following:

• You will need someone to drive you home from the surgery center. (Your vision will usually be a bit blurred immediately after LASIK.)

• You will be instructed to use medicated eye drops for about a week after LASIK to protect your eyes from infections.

• You will usually be instructed to wear protective eye goggles when you sleep for the first week after LASIK.  This keeps you from rubbing your eyes in your sleep.

•  Your eyes may feel dry for several weeks after LASIK.  You will be given instructions on how often you should use artificial tears to keep your eyes moist and comfortable.

•  You may be more sensitive to bright light for several weeks after LASIK.  You may be instructed to wear sunglasses outdoors.  (Make sure they block 100 percent of the sun's UV rays.)

• Don't rub your eyes after LASIK until your eye doctor tells you it is safe to do so.

• Don't go swimming for at least one week after LASIK.

• You may notice mild fluctuations in the clarity of your vision for a few weeks after LASIK.  If so, discuss this with you eye doctor at your post-operative visits (see below).

Your LASIK surgeon may give you additional instructions as well.  You can usually return to work the day after your LASIK procedure. 

LASIK post-operative care

Your eye doctor will want you to return for several visits after your LASIK to make sure your eyes heal properly and to monitor your visual acuity.  Follow-up visits are usually scheduled at least at the following milestones (at the minimum):

• 1 day after LASIK

• 1 month after LASIK

• 3 months after LASIK

At the 3-month visit, your vision should be clear and stable and your eyes should be moist and comfortable. 

Approximately 90 percent of people who have LASIK are very pleased with their vision at their 3-month visit.  But about 10 percent may need a second LASIK treatment (called an enhancement) because their vision is not clear enough.  When needed, enhancements are usually performed about six months after the first LASIK procedure. 

Risks and complications of LASIK

LASIK is popular because it's very safe and effective.  But like any surgery, it's not risk-free.  Some of the risks your eye doctor may discuss with you include:

• Sensitivity to bright lights (usually temporary).

• Dry eyes (usually temporary).

• Glare or streaks/halos around bright lights (usually temporary).

• Under-corrections and over-corrections that require an enhancement (about a 10 percent risk).

• Wrinkling of the corneal flap that requires repositioning of the flap (infrequent).

• Permanently blurred vision after LASIK that cannot be corrected with eyeglasses, contact lenses or an enhancement (very rare).

• Infection of the cornea, leading to scarring and permanently blurred vision (very rare).

Be sure to ask your eye doctor any questions you have about these and other possible risks and complications prior to signing a surgical consent form and proceeding with LASIK surgery.