LASIK Surgery
LASIK eye surgery (laser assisted intrastromal keratomileusis) is a computer-assisted surgeon-controlled procedure that improves vision (nearsightedness, farsightedness and astigmatism) by permanently changing the shape of the cornea (the clear covering of the front of the eye) with cool excimer lasers (ultraviolet light). The procedure takes about five to ten minutes per eye depending on the type and amount of correction required, and is performed on an outpatient basis at Horizon Laser Vision Center. The surgeon determines the amount of the treatment (vision correction) required with the help of WaveScan® technology and programs the patient's unique corneal shape and refractive error (glasses prescription) into the computer prior to the procedure.
View movie: LASIK Introduction (requires Flash player)
View movie: LASIK: Step by Step (requires Flash player)
LASIK eye surgery is performed with two main instruments. One is a very precise microsurgical instrument called the Hansatome microkeratome. The other is the FDA-approved VISX Star S4™ Excimer Laser System. This laser system includes a large machine with a microscope and a computer screen attached to it. The VISX Star S4 Laser also includes an eye tracker that follows and compensates for any eye movements during the procedure.
Immediately preceding the procedure, numbing drops are placed in the eye and the area around the eye is cleansed. A small instrument called a lid speculum holds the eyelids open to prevent blinking.
Using a surgical microscope the doctor affixes a suction ring to the eye. The microkeratome is attached to the suction ring and high pressure is applied to create suction to the cornea and to make it firm.
The doctor uses the microkeratome to create a flap across the corneal surface. The flap remains attached to the cornea with a hinge at the top of the cornea under the upper eyelid. The microkeratome and the suction ring are then removed. The doctor lifts the flap, folds it back on its hinge, and dries the exposed tissue ready for the laser treatment. This step takes 15 to 20 seconds.
To position the eye for the procedure, the patient is asked to focus on a light within the machine. When the eye is in the correct position, the doctor starts the laser. While looking through the microscope, the surgeon uses the excimer laser to reshape the cornea. This is achieved by vaporizing an ultra-thin amount of the exposed corneal tissue. This step takes ten to 60 seconds.
Upon completion of the laser treatment, the surgeon replaces the flap, ensures it is correctly repositioned, and rinses the interface. Generally, keeping the flap in position requires no stitches (sutures) because a natural suction mechanism within the cornea holds the flap in place. A thin scar will form around the edge of the flap increasing the adhesion. Because this healing is in the periphery of the cornea, it does not affect vision.
Proper pre-surgery preparation and post-surgery eye care are key to the success of this procedure.
LASIK resembles PRK in that both procedures use the excimer laser to change the refractive error. However, because the surgeon creates the flap, LASIK preserves the corneal surface. As a result, the surface of the eyes treated with LASIK heals faster than those treated with PRK. Most patients achieve reasonable vision the day following the surgery. Furthermore, patients experience less discomfort with LASIK post-operatively than with PRK.
Additional information on LASIK eye surgery is available from the U.S. Food and Drug Administration.
