LASER Terminology | Laser Surgery | Laser Surgery FAQs

Refractive Surgery

Refractive surgery is a surgical method of vision correction by changing the front surface (cornea) of the eye.

Excimer Laser

The excimer is a type of laser used in all laser refractive surgical procedures in order to reduce and/or correct the prescription. The laser utilizes a 193 nm argon-fluoride beam to reshape the corneal tissue by breaking collagen bonds and removing corneal tissue. The laser is focused more centrally to correct the myopic (near-sighted) eye and is focused more peripherally to correct the hyperopic (far-sighted) eye. The excimer laser is so precise it can remove one micron of tissue, which is approximately one-hundredth the width of a human hair.

Laser Assisted in Situ Keratomileusis (LASIK)

LASIK is used to correct myopia, hyperopia, and astigmatism. First a microkeratome is used to create a thin flap of tissue (120 to 180 microns thick) and then the excimer laser is used to reshape the corneal tissue below. The flap is then laid back down sealing the lasered area. Typically, vision recovers quickly and many patients can drive the next day.


The microkeratome is the instrument used for the creation of a flap during the LASIK procedure.


Pachymetry measures the thickness of the cornea. Several different instruments can be used to determine the corneal thickness, such as ultrasound or wave reflections of optical light. This is a critical value to obtain prior to surgery, because if there is not enough corneal tissue, then the patient is not a candidate.

Photorefractive Keratectomy (PRK)

PRK is a type of laser procedure, which involves the removal of the surface corneal tissue by gentle scraping. Next, the excimer laser is used to reshape the cornea and a bandage soft contact lens is worn for several days.

Phototherapeutic Keratectomy (PTK)

PTK uses the excimer laser to treat irregular corneal surfaces. This is a medical technique to manage eye health problems. Candidates for PTK may include patients with visual compromise due to corneal scars, dystrophies and/or irregular corneal astigmatism. It also can be used to treat recurrent corneal erosions.

Radial Keratotomy (RK)

RK is an older refractive surgical procedure which was popular in the 1980s. It treated low amounts of near-sightedness by creating radial incisions (like the spokes of a wheel) in the peripheral cornea, using a diamond-blade knife. The laser was not a component of this procedure.

Customized Refractive Surgery

Custom surgery is based on wavefront-driven excimer laser photoablation. Wavefronts represent the natural occurring aberrations within our eye and these optical aberrations are as unique as a person’s fingerprint. Once a patient’s wavefront is captured, it is incorporated into the surgery and the treatment is customized for the individual patient’s eye.


Topography maps the surface of the cornea. Several thousand data points are collected which analyze the elevation and curvature of the cornea.

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