Understanding LASIK

LASIK is a shortened term standing for "LAser in SItu Keratomileusis". This correction procedure utilizes two devices to alter the degree of near-sightedness in an eye. These two devices are the excimer laser and the microkeratome.

How LASIK is Performed

Step 1

Picture of LASIK Tool

After anesthetic eyedrops are put on the eye, a suction ring is centered over the cornea of the eye. This suction ring stabilizes the position of your eye and increases the pressure to a level that is needed for proper functioning of the microkeratome. The guide tracks on this suction ring are used to provide a precise path for the microkeratome.

Step 2

Picture of LASIK Tool Retracted
Picture of Lasik Tool Moved Over Eye

The microkeratome is a very precise instrument that is the "keystone" in the LASIK procedure. This device is a mechanical shaver that contains a sharp blade that moves back and forth at high speed. This shaver is placed in the guide tracks of the suction ring and is advanced across the cornea using gears at a controlled speed. This process creates a partial flap in the cornea of uniform thickness. The flap is created with a portion of the cornea left uncut to provide a hinge.

Step 3

Picture of Corneal Flap

After the suction ring and microkeratome have been removed, the corneal flap is folded back on the hinge exposing the middle portion of the cornea.

Step 4

Picture of Laser Pulses/Cornea Flattened

The excimer laser is then used to remove tissue and reshape the center of the cornea. The amount of tissue removed is dependent upon the degree of near-sightedness that is being corrected. This portion of the LASIK procedure is almost identical to the PRK procedure, except that in the PRK the surface of the cornea is treated without the creation of the corneal flap.

Step 5

Picture of Flap Replaced/Central Cornea Flattened

In the final step, the hinged flap is folded back into its original position. The front surface of the eye is now flatter since the flap conforms to the underlying surface. In effect, the change made in the middle of the cornea is translated to the front surface of the cornea.

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Precision of the Laser
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