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 Doctors
have been routinely treating nearsightedness, farsightedness and
astigmatism with incisions for over 25 years. By the early 1980’s they
began looking at lasers to improve the precision and predictability of
altering the shape of the cornea. Researchers found that IBM’s new
Excimer Laser, used initially in etching computer chips, had medical
applications as well. Now in its second decade of use, the
technologically advanced Excimer Laser has added a tremendous amount of
precision, control and safety to treating nearsightedness,
farsightedness and astigmatism.e
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On the right, we show a
normal eye before any type of refractive procedure. The dark purple
layer on the outer part of the cornea is called the epithelium. This
protective outer layer is always left intact with the LASIK procedure as
opposed to other visioncorrection options. The Lasik procedure starts by
completely numbing the eye with "eye drop" anesthesia; then an
eyelid holder is placed between the eyelids to prevent blinking.
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The device on the left is
called a microkeratome. With it, the doctor slices the cornea from the
side, creating a flapz. A part of the device flattens the cornea during
the slice, to create a flap of uniform thickness. It is at this stage of
the procedure that the doctor must exercise extreme precision and
caution to create a perfect flap. |
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On the right is a cross
section view of the procedure performed by the microkeratome. The result
is a uniform flap with a hinge, which the doctor rolls back to expose
the inner layers of the cornea.
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With the flap folded back,
the doctor now corrects the refractive error by applying the laser
treatment to the exposed corneal tissue. |
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The procedure is
complete when the flap is repositioned. The eye has a natural suction
facility that keeps the flap firmly in place. Care is taken by the
doctor to ensure an excellent fit when repositioning the flap. Because
very little of the epithelium has been disturbed, patients report a high
comfort level after the procedure. |
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