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Today LASIK (Laser
Assisted Intra-stromal
Keratomileusis) is the most
commonly performed procedure to correct
nearsightedness, farsightedness and
astigmatism.
Corrective eye surgery has changed people’s
lives for decades. The first procedure
performed was called RK. However, as a
result of new techniques and scientific
advances, patients have more options.
LASIK permanently changes the shape of the
cornea, the clear covering of the front of
the eye, using an excimer laser. A knife,
called a microkeratome, is used to cut a
flap in the cornea.
A hinge is left at one end of this flap. The
flap is folded back revealing the stroma,
the middlesection of the cornea. Pulses from
a computer-controlled laser vaporize a
portion of the stroma and the flap is
replaced.
The cornea is a part of the eye that helps
focus light to create an image on the
retina. It works in much the same way that
the lens of a camera focuses light to create
an image on film. The bending and focusing
of light is also known as refraction.
Usually the shape of the cornea and the eye
are not perfect and the image on the retina
is out-of-focus (blurred) or distorted.
These imperfections in the focusing power of
the eye are called refractive errors.
There are three primary types of refractive
errors: myopia, hyperopia and astigmatism.
Persons with myopia, or nearsightedness,
have more difficulty seeing distant objects
as clearly as near objects.
Persons with hyperopia, or farsightedness,
have more difficulty seeing near objects as
clearly as distant objects.
Astigmatism is a distortion of the image on
the retina caused by irregularities in the
cornea or lens of the eye. Combinations of
myopia and astigmatism or hyperopia and
astigmatism are common.
Glasses or contact lenses are designed to
compensate for the eye's imperfections.
Surgical procedures aimed at improving the
focusing power of the eye are called
refractive surgery. In LASIK surgery,
precise and controlled removal of corneal
tissue by a special laser reshapes the
cornea changing its focusing power.
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Click here
for larger animated images |
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MYOPIA
(Nearsighted) |
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HYPEROPIA
(Farsighted) |
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ASTIGMATISM |
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LASIK |
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Light rays are focused
in front of the retina instead of directly on the retina |
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Light rays are not bent
enough to focus directly on the retina |
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Light rays are focused
at more than one point on the retina |
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The Cornea is reshaped
so light rays can focus directly on the retina |
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