LASIK and other forms of laser refractive surgery, such as PRK and LASEK, all use a highly specialized excimer laser to reshape the cornea and correct refractive errors including myopia (nearsightedness), hyperopia (farsightedness), and astigmatism.

Excimer lasers have revolutionized the field of laser eye surgery, and over the decades have greatly increased in safety, efficacy and predictability of corneal refractive surgery outcomes.

LASIK Excimer lasers have the ability to remove, or “ablate,” microscopic amounts of tissue from the cornea’s underlying stromal layer, with a very high degree of accuracy, and without damaging the surrounding corneal tissue.

Several FDA-approved excimer lasers are on the market, but one is not necessarily “better” than another. A few of these lasers include the Alcon EX500, AMO VISX S4 IR, Bausch & Lomb Technolas TENEO 317, & Zeiss MEL 80 Excimer Laser, just to name a few. The most suitable excimer laser for a practice will depend on the surgeons specific requirements, such as the degree of refractive error, the size of patient’s pupils, and the thickness of the cornea.

Most experts agree that a surgeon’s skill and experience, and an accurate evaluation of a patient, determine whether or not an individual is a suitable LASIK candidate. Typically, there are far more critical factors affecting final LASIK outcomes than subtle differences between excimer lasers.

Types of Modern Excimer Lasers Used for LASIK

In the United States, all approved LASIK & LASEK Excimer lasers meet safety and effectiveness criteria established by the FDA. The main differences among LASIK lasers are the patterns they use to deliver the laser beam and track the eye during laser eye treatment.

Spot scanning lasers. Spot scanning lasers, which are the most common, use small-diameter laser beams (0.8 to 2 mm) scanned across the cornea to produce the treatment zone. This approach has the potential to produce the smoothest corneal treatments, allows customized treatments, and also treats irregular astigmatism.

Slit scanning lasers. Slit scanning lasers use relatively small beams linked to a rotational device with slit holes which enlarge. The laser beams scan across these holes during surgery, producing a gradually enlarging ablation zone. This approach produces a uniform beam that creates smoother treatments than older broad-beam lasers. However, slit scanning lasers have the potential to cause a slightly greater risk of decantation & overcorrection, unless an eye tracker is used, or with an inexperienced surgeon.

Wavefront-guided lasers. Many LASIK Excimer lasers, whether spot or slit scanning, are connected to a device that detects and “maps” defects in the eye’s optical system, based on how light travels through the eye. These Wavefront devices produce a custom LASIK treatment that is unique to each patient. Both slit scanning and spot scanning lasers can be used for Wavefront-guided treatments.