What Kind of Laser Is Used in Laser Eye Surgery?

Laser eye surgery is a method of vision correction that does not require the patient to wear corrective eyewear like glasses or contact lenses. Laser surgery is considered refractive surgery, and generally corrects vision problems by altering or changing the shape of the cornea of the eye. Refractive surgery has been available since the early 1900s but did not become effective until the 1970s when the radial keratotomy procedure was developed to use incisors to alter the curve of the cornea. Refractive surgery was revitalized in the 1980s with the first use of a laser--the excimer laser--to alter the corneal shape.

Lasik

• Today, the most common form of laser eye surgery is Laser in-Situ Keratomileusis. Laser in-Situ Keratomileusis is commonly called LASIK and is a 2-stage process. The first step is to make a horizontal cut along 90 percent of the eye's cornea using an Intralase FS laser. The laser creates a flap which can be folded away from the cornea. The cornea is then reshaped with the excimer laser, and the flap is then returned to its initial position. The cornea is able to heal itself almost immediately and no stitches are required after the flap is put back into place.

The Intralase Laser

• The intralase FS laser is a femtosecond laser which is revolutionary to the ophthalmology field. It is computer controlled and far safer than previous techniques for cutting the flap of the cornea, which involved the use of a microkeratome. The microkeratome used a vacuum effect to pull the cornea into a suction ring where it was held in place as a metal blade cut the flap. Now, the laser is able to cut the flap without the complications related to the use of the metal blade on the eye.

Intralase Laser versus Excimer Laser

• The intralase FS laser and the excimer laser work very differently in the process of laser eye surgery. The excimer layer is very precise, and is able to remove individual microns of tissue from the corneal layers to shape the cornea. The intralase FS laser, on the other hand, uses a more rapid-fire laser which targets 3 microns at a time. Thus, the intralase FS laser is able to use less energy on the corneal tissue than the excimer laser.

  Furthermore, the excimer laser and the intralase laser have different wavelengths. The excimer layer has a wavelength of 193 nm, which is absorbed by the cornea and has an effect upon contact. The intralase laser, with a longer wavelength of 1053, can pass through the cornea without causing ablation of the tissue (destroying the tissue) until it reaches a specific target.

PRK

• PRK was the original procedure that preceded LASIK. Over 1 million PRK procedures have been performed since its first use in the 1980s. Although the excimer layer was used in this surgery as well, the absence of the intralase laser made the procedure more difficult to recover from. While LASIK patients heal almost immediately after the surgery, the PRK procedure used to have a healing time of up to 6 months before vision stabilized. There were also higher risks of pain associated with PRK than with LASIK.

Custom Cornea LASIK

• Custom Cornea LASIK is a new laser eye procedure which involves the use of a wavefront analyzer. This wavefront analyzer allows doctors to perform custom laser treatment by mapping the errors in the eye to correct the refraction problem. Surgeons can use the wavefront analyzer to create a 3-dimensional map of the entire eye, while before only a topographical map was available.