Laser in situ keratomileusis (LASIK) uses an excimer laser to correct nearsightedness, farsightedness, or astigmatism by removing a thin lenslet of tissue from the cornea (the clear, front lens of the eye).

In LASIK, a pancake-like thin flap of the cornea is first prepared, either with a laser called Intralase or with an instrument called a microkeratome. Here at the Cornea and Laser Eye Institute - Hersh Vision Group, we use the all-laser technique exclusively. The flap acts to preserve the surface epithelial cells to promote quick healing and recovery of vision. Next, the Wavelight excimer laser is used to remove a small amount of tissue from the corneal bed beneath the flap (analogous to removing a "tissue contact lens"). The excimer laser uses a mixture of gases to produce a beam of invisible ultraviolet light energy, which when applied via an eye tracking mechanism, results in meticulous removal of this tissue lens.

The LASIK procedure concludes when the corneal flap is repositioned. When the flap is replaced, it lies in the bed of excimer laser removed tissue, causing the surface to change shape with the effect of decreasing nearsightedness, farsightedness, or astigmatism.

LASIK procedures are performed under topical anesthesia (eyedrops) and are not painful. A lid retainer supports your lids to avoid blinking during the procedure and a "laser radar" eye tracking mechanism compensates for any eye movements. At the end of LASIK, clear protective eye goggles are placed. You will use drops to avoid infection and control inflammation for one week.

You are generally comfortable after the LASIK procedure. There may be a little stinging. Vision usually begins to improve the morning after the treatment. Most people can work the next day; however, you will be seen for an examination on that day.

There are two basic types of possible side effects with LASIK. Because patients may respond and heal differently, it is possible that the entire refractive error may not be corrected or that there might be some overcorrection. If you are undercorrected, your vision will be clearer without glasses, but less powerful glasses may still be necessary to fine tune to your best vision. For some patients who are overcorrected, especially those patients who are somewhat older, reading vision might be difficult without glasses. Furthermore, older patients, 40 years and older, may require reading glasses after the procedure. Patients who are undercorrected or overcorrected usually undergo a retreatment procedure to further improve their vision.

We will discuss the possibilities of under and overcorrection in your particular case and what you may reasonably expect to achieve visually. In general, around 10% of patients will undergo a retreatment enhancement procedure to further improve vision if it is not clear after 3 months. In addition, other optical side effects include haloes around lights and glare, especially at night. These side effects have been improved with the new Wavelight LASIK procedure. The other group of relatively rare complications may be secondary to problems with the LASIK surgery itself and subsequent corneal healing. We will discuss these possibilities in detail.

Although most excimer laser treatments today are done with the LASIK technique, some people may be better off with the surface LASEK/PRK procedure. Our preoperative examination and measurements determine our recommendation of the procedure which would be best in your particular situation.

In general, possible benefits of LASIK as compared with LASEK/PRK:

(1) Tissue removal beneath a flap rather than at the surface preserves the surface corneal cells (epithelium) with the advantage of faster visual recovery for the patient

(2) Postoperative discomfort is reduced

(3) Tissue removal beneath a flap may decrease the risk of haze or scarring

Some risks of LASIK as compared with LASEK/PRK include:

(1) Surgical risks (these are rarer with surgeons experienced in LASIK)

(2) Damage to the corneal flap

(3) Difficulties with the flap postoperatively

In depth articles and studies:

PRK Versus Lasik
LASIK Retreatment