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Custom LASIK
Custom LASIK differs from conventional LASIK in that
the measurements of your eyes that are used for laser
vision correction are made more accurately and precisely.
With conventional laser vision correction procedures,
the standard measurements for glasses are used by the
laser to correct your nearsightedness and astigmatism.
With custom LASIK, a wavefront machine measures all
the imperfections unique to your eyes, with 25 times
more precision than the standard measurements for glasses.
So, custom LASIK provides you with a more precise and
individualized approach to laser vision correction.
What does that mean to me? Will I notice a
difference?
In the FDA study using the custom treatment (CustomVue)
on the Visx Star
S4 laser, 70% of patients could see better than
20/15 without glasses or contacts. In that same study,
98% of patients could see 20/20 or better without glasses
or contacts. On the whole, patients said their night
vision was better after treatment as compared to night
vision before the procedure with glasses and contacts.
With custom lasik, you have a greater chance of 20/20
or better uncorrected vision, when compared to conventional
lasik.
Can anyone get customized lasik?
Custom lasik using CustomVue with the Visx Star S4 laser
is currently approved for nearsightedness,
farsightedness,
and astigmatism.
Your doctor can tell you if you meet the specific criteria.
In addition, there are some patients who should have
conventional lasik. These patients may not do as well
with custom lasik. Only your eye care professional can
tell you if custom lasik is best for you. Remember,
conventional lasik is not “second best”;
it does provide excellent results. As an analogy
to highlight the difference between conventional and
custom lasik, conventional lasik is like getting fit
with a very expensive, off-the-rack suit, whereas custom
lasik is like getting a suit custom fit by a Hong Kong
tailor. You can "look" great with either.
Custom LASIK procedure and “wavefront”
First, a wavefront machine is used to measure your
eyes. The wavefront machine used with the Visx Star
S4 laser, is called the WaveScan. The
WaveScan machine measures your eyes using light; it
is non-invasive and does not hurt. A harmless beam of
light is directed into your eye. The light passes through
your cornea (the clear window or covering of your eye),
through the pupil and lens, and then is reflected by
the retina (the inner lining or “film” of
the eye). The reflected light bounces back out the way
it came, through the lens, pupil, and finally, the cornea.
The WaveScan machine measures how the light comes back
out.
When doctors talk about “wavefront”, they
are referring to the shape of the light as it moves
through space. When the light beam from the WaveScan
enters an eye, it has a perfectly flat wavefront. Picture
the waves that wash ashore at a beach. The edge of the
water is generally a fairly straight line. In theory,
a perfect human eye would reflect back a light beam
with its wavefront still flat. But the human eye is
not perfect, there are imperfections in the optical
system of the eye. These imperfections could come from
a cornea that has scars or is not shaped perfectly,
or from a lens that is not perfectly shaped. In such
an imperfect system, light may go into the eye with
a perfect wavefront, but it comes out with an irregular
wavefront. Picture how the waves of water washing ashore
on a beach appear, if there are rocks sticking out from
the sand. Rather than looking like a straight line,
the edge of the advancing water is irregular, perhaps
lagging where it was obstructed by the rocks. 
The WaveScan records the wavefront of your eye and
generates a picture called a WavePrint map.
Your WavePrint map is like a “fingerprint”
of your eye; no two eyes have the same WavePrint map.
The wavefront data is converted into a complex mathematical
formula. This information is transferred to the Visx
Star S4 laser. Your eye surgeon first creates the lasik
flap. The laser then lays down the treatment that corrects
the imperfections of your eye, with the goal of making
the wavefront flat or ideal.
Custom LASIK and Iris Registration
Iris Registration (IR) is an exclusive VISX laser technology
that allows precise matching of treatment calculations
to the actual eye undergoing laser treatment. When a
patient elects for CustomVue, VISX’s customized
laser treatment, the WaveScan instrument captures the
measurements of a patient’s eye. Since the laser
treatment is done on a separate machine, the Star S4,
it is very important to make sure the planned treatment
measurement precisely matches the actual eye under the
laser. The eye can rotate when a patient goes from the
sitting position (the situation when WaveScan is used)
to the lying down position (the situation when the Star
S4 laser is used). Both the WaveScan and Star S4 laser,
has software that can identify iris landmarks which
are unique to each patient’s eyes. By comparing
the picture of the iris, capture by the WaveScan, to
its own, live picture of the eye under the laser, the
Star S4 laser, can adjust the treatment orientation
to the actual orientation of the eye under the laser.
This helps to fully realize the potential of customized
treatments, resulting in superior vision results.
The PreVue Lens
The PreVue lens is an option with the CustomVue
lasik procedure. Once your WaveScan measurements
are taken, a plastic lens is placed under the Visx Star
S4 laser. Your unique correction is created on the lens.
The lens is fitted into a frame for viewing, so you
can “preview” an approximation of the potential
result after custom lasik using CustomVue. Not everyone
needs to have this preview. Your doctor can best advise
you.
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