Laser in-situ keratomileusis (LASIK) is by far the most popular refractive surgery procedure. The first LASIK procedure was performed in 1991, and hundreds of thousands of Americans have the procedure done each year.

LASIK is a two-step procedure: (1) A thin flap is created in the cornea, and (2) the underlying corneal tissue is reshaped with a laser.

In the first step, the surgeon can use either a bladed surgical tool (called a microkeratome) or a femtosecond laser to make the corneal flap. Whichever method is used, the flap remains attached to the cornea by a small hinged area. The flap is folded back on this hinge, exposing the underlying bed of the cornea.

In the second step, an excimer laser beam sculpts the curvature of the exposed cornea by ablating (vaporizing) tissue. The excimer laser is called a "cool" laser because it can precisely ablate tissue without causing thermal damage to the surrounding tissues.

After the laser ablation, the corneal flap is repositioned over the treatment area. The flap seals relatively quickly without the need for stitches.

LASIK has quickly become the dominant refractive surgery because it is essential painless and visual recovery is typically rapid. LASIK can treat both myopia(nearsightedness) and hyperopia (farsightedness) with or without astigmatism.

Since the advent of LASIK, advances have been made such as wavefront-guided LASIK, also known as custom LASIK. This uses a computerized corneal map of the cornea to create a more detailed and customized laser treatment. In addition to correcting nearsightedness, farsightedness and astigmatism, wavefront-guided LASIK can also correct smaller optical imperfections of the eye called higher-order aberrations, which are unique to each individual.

Because of its added precision, wavefront-guided LASIK may produce better visual outcomes than standard LASIK, but it also results in higher procedure cost. Benefits include: