The word LASIK means “Laser-Assisted In Situ Keratomileusis.” In situ is latin and means to deal with a phenomenon in place where it occurs, as opposed to outside of it’s environment. Keratomileusis is a surgical improvement of the refractive state of the cornea. It is performed by lifting up the front surface of the eye by forming a thin hinged flap, under which the shape of the cornea is changed by using some type of surgical device.
Excimer Lasers
LASIK eye surgery is therefore surgery that is done in order that a person who wears glasses or contact lenses should no longer be completely reliant on them to see. It is a medical procedure undertaken by a qualified opthamologist. The aim is to modify the shape of the cornea (the clear covering of the front of the eye) through use of an excimer laser. An excimer laser is a type of ultraviolet chemical laser that is unusually well focussed and capable of highly delicate control. Instead of burning away or cutting materials, an excimer laser intrroduces sufficient energy to disrupt molecular bonds of surface tissues. Effectively the tissue disintegrates in a controlled fashion through ablation rather than burning. Excimer lasers can remove very thin layers of surface material with almost no heating or change to the material which is left behind.
Flap Creation
When LASIK surgery is performed, a knife known as a microkeratome is inserted into the cornea and cuts a flap of skin. A human cornea measures from around 500 to 600 micrometres in thickness; the microkeratome creates a 100 to 200 micrometre thick flap. At one side of the flap is left a small piece of skin known as a hinge. The flap of skin is then gently folded back to show the stroma (otherwise known as the middle area of the cornea).
There are two types of microkeratomes currently in use, mechanical and laser. Both are affixed to the eye by use of a 360 degree vacuum ring, flatten the cornea with a clear plate, then cut the cornea underneath the plate.
Mechanical microkeratomes use a sharp thin metal blade. Laser microkeratomes are used in the IntraLasik procedure. They employ amplified light energy to form thousands of minute bubbles at a predetermined depth. These bubbles of water and carbon dioxide connect with each other create an incision.
Reshaping the Stroma
A laser that is controlled by a computer is then used to disintegrate a part (but not all) of the stroma and after that is finished, the flap of the cornea is fixed up and put back into place. New and more advanced ways of performing LASIK surgery are being looked at all of the time.
The purpose of eyeglasses and contact lenses is to compensate for the weaknesses of the eyes and to allow for vision that is as clear as can be. LASIK is a form of refractive eye surgery that is geared towards improving the eye’s ability to focus and not just focus, but also focus well on any object. When it comes to LASIK surgery, a laser is used to remove part of the tissue of the cornea and then it is reshaped in order to improve its ability to focus.
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