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This is the most applied
method among the methods specific to the eye. It is mostly used
in patients with hyperopia and astigmatism. However the field it
is most useful in is the eyes with a previous failed treatment.
In such conditions, it recorrects the failed or mistreated part
while preserving the successfully treated regions. |
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The most important
part of this method is the special eye map called
topography. This map is recorded with specially developed
devices and can be copied using a special method.
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This map is recorded to a computer disk and transmitted to the
computer of laser which is going to make the treatment. The disk
can only be read by the computer of laser. |
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Laser prepares a
treatment plan according to the map it reads with all
details. There is also a role of wavefront method in this
plan The treatment plan will be made by laser assessing both
wavefront and map results.
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System
determines the shape which cornea layer is expected to have
after treatment and the treatment is applied.
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The application of treatment is not different from standard
laser applications for the patient. The whole difference is
the preparation of treatment and the feature of the shape
that laser creates on cornea.
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The direct image
taken from cornea and analyses of this image are found in
general view of cornea topography map.
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The 3D view of cornea
is also obtained from this map analysis. The ideal condition
of cornea expected after laser treatment is reckoned
according to these maps.
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If cornea
becomes too steep like in this blue circle, the patient will
see his surrounding very blurry while seeing well from the
centre.
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If cornea is
too flat like in this red circle, patient will see the
surrounding well while seeing the centre i.e the point he is
looking at blurry.
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If cornea has a
completely round shape which is thought to be ideal, there
will be many focus points as shown in this diagram and the
patient will not have an excellent vision.
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The desired and
targeted form of cornea is this red circle form. If this
shape of cornea can be obtained after laser treatment, the
vision will be perfect. This perfect vision will continue
night and day. The surgeon applying the treatment can define
the ideal form he determines for cornea to the computer and
conducts the treatment to reach this form in the method
called Q-mode or F-CAT.
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WHAT IS WAVEFRONT LASIK?
The
Wavefront LASIK, is a LASIK technique using the wavefront
technology to adjust the cornea in a personal way for each
patient in order to adjust the vision. In adequate
candidates, the wavefront LASIK can produce better results
than standard LASIK treatment.
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WHAT IS THE WAVEFRONT TECHNOLOGY?
After the developments in the adaptive optics field
achieved in the recent years, the elimination of the
distortions disturbing the vision has become possible.
The wavefront technology, used for obtaining sharper
telescope views, has begun to be used in the
ophthalmology field to further improve the optical
system of the eye.
The wavefront technology measures the
aberrations/distortions (cumulation of all the rays in
one point/bending), creates a mathematical definition
and determines the amounts numerically. Transferring
these data to a point-scanning laser such as
'Allegretto?, allows you to shape the cornea personally
for each patient and to adjust the existing distortions.
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HOW ARE THE ABERRATIONS MATHEMATICALLY DEFINED?
The Zernike polynomials are the mathematical definitions of
the aberrations (defects) in sight. Polynomials have
different levels and orders. Low level polynomials comprise
myopia, hypermetropia and astigmatism. Low level aberrations
can be easily treated with glasses or standard LASIK
treatment. High level polynomials are recently defined.
Coma, trifoil and spherical aberration are the most common
high level aberrations. The graphic shows some high level
aberrations (Fig. 3). Wavefront LASIK, is adjusting the high
level aberrations which can not be treated with standard
LASIK treatment.
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Fig 4. The picture on the left is the wavefront map of an
eye with spherical aberration and the one on the left is the
blurred sight resulting from such disorder |
WHO ARE THE CANDIDATES FOR VAWEFRONT LASIK?
This technology can be used for two groups of patients.
The first group is the patient group applying for the
standard LASIK treatment. There is evidence on the fact that
the Wavefront LASIK provides a higher quality of sight and
less night vision side effects. The second group consists of
the patients who previously had experienced LASIK, PRK,
LASEK or other retractive surgeries and continue to face
problems. These problems may include night dazzles, halos,
sight quality problems or insufficient treatment of the
sight defects. The cornea widt and the overall health
condition of the eye are important in determining whether or
not to perform a second operation.
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