Custom
LASIK vs Traditional LASIK
One
place to start in describing the difference between traditional LASIK
surgery and the latest Custom LASIK surgery is by understanding the
language used in the vision industry to describe vision problems that
are corrected by the two technologies.
There
are two classes of vision problems in this discussion and they are called
Higher order aberrations and Lower order aberrations. An aberration
refers to a vision imperfection or visual distortions in your eye.
Traditional
LASIK surgery is thought to handle Lower order aberrations - your near
or farsightedness and astigmatism. Custom LASIK is supposed to correct
both lower and higher order aberrations - night vision and halos around
lights. Before going any further, if you do not have Higher order aberrations,
(about 15% of patients have significant higher order aberrations) then
Traditional LASIK will probably work for you.
Given
that the new technology is usually more expensive, the first question
to consider is, "How do I know whether I have higher order aberrations?"
This
is a two-part answer. The obvious response is that in order to know
whether you should have Custom LASIK, the LASIK practice you talk with
MUST have a Wavefront machine to do the examination to determine
if you have higher order aberrations. If you go for a LASIK consult/exam
with a doctor who does not offer Custom LASIK, you obviously will not
be tested for higher order aberrations.
The
fuzzy answer is that depending on your vision prescription, a LASIK
practice will know if there is a good chance you may have higher order
aberrations and refer you to someone who does the Wavefront exams.
In our surveying of LASIK practices we have found the range of responses
too varied to give a simple answer.
The
second question is, "If I have higher order aberrations and I choose
traditional LASIK, how much will my vision be affected?
There
is no definite answer to this question. I suppose if having excellent
night vision and avoiding halos are, for your lifestyle, very important
then you should probably get the Wavefront exam just to be sure.
Here
is a comment from an industry expert, "Everyone has higher order
aberrations to some degree or another unless they have a perfect optical
vision system. The amount of higher order aberrations is now measurable
with Wavefront technology."
Besides
the money thing, there seems to be little evidence (it is FDA approved)
that Custom LASIK would be a bad choice.
And
third, "If I don't have many higher order aberrations and I get
Custom LASIK will my vision be better, worse or the same as with Traditional
LASIK?"
Definitive
answers when it comes to eye surgery are always impossible. The same
industry source replied, "If you have been living all your life
with only a small amount of aberration and now you have the conventional
surgery and it induces aberration that you have never had to deal with
then you may be unhappy whereas if you have the custom procedure we
know that induces very little aberration and will probably be happier."
Surprisingly
correcting your near or far-sighted vision (your lower order aberrations)
with either Traditional or Custom LASIK can make your higher order aberrations
worse! The one chart sent to me by an industry insider showed that
Wavefront LASIK caused less new higher order aberrations than conventional
LASIK surgery. There is no way to know how much a .12 difference in
higher order aberrations makes when it comes to actual vision.
While
I find technical discussions on the technology of the laser, the Custom
LASIK process and the in-depth particulars of vision conditions to be
more than the average person (this includes me) can completely understand,
there are a few things we should cover.
The
major difference in the two technologies is how the eye is measured.
In traditional LASIK, the surface cornea was viewed by a topographical
eye measurement system.
In
Custom LASIK, a light beam is used to see inside your eye and measures
more than just the surface of the cornea. This is how it is able to
detect "higher order aberrations."
Traditional
LASIK surgery uses your prescription (my nearsighted vision was a -4.5)
to determine the laser settings. The laser setting for my Traditional
LASIK surgery (November 2000) was for people with -4.5 vision.
Custom
LASIK is supposed to treat all -4.5 eyes differently as each eye is
unique. Broadly, this is one way to think about the two procedures.
While
reading various results so far from Custom LASIK procedures, the reduction
of glare and improvement in night vision seem to head the list of most
significant gains from using the new technology.
The
newest advances in laser eye surgery focus on accuracy and customization.
Two companies have been recently FDA approved to provide these advances
to the public and a third is under review.
LADARWave™
CustomCornea®
In
October of 2002 the FDA Ophthalmic Devices Panel unanimously recommended
approval for the Alcon LADARVision Custom Cornea wavefront-guided laser
vision correction system for Nearsightedness (Myopia) up to -7 and -3
astigmatism. The Alcon LADARWave™ CustomCornea® Wavefront System is
a form of LASIK that lets your ophthalmologist sees refractive aberrations
in clear and accurate rotating 3D images.
Their
link: http://www.ladarvision.com/decision/CustomCornea_diff_flash.asp
Visx
CustomVue™
The
Visx CustomVue™ WaveScan technology was FDA approved in May of 2003.
CustomVue™ WaveScan is a new diagnostic system that captures a "fingerprint"
of the eye which is said to be 25 times more precise than what was previously
measurable by standard methods for glasses and contact lenses. It has
been approved for Nearsightedness (Myopia) up to -6 myopia and -3 astigmatism.
Bausch
& Lomb Zyoptix™
The
very latest development in laser eye treatment from Bausch and Lomb
is a system called Zyoptix. From their press release - The Zyoptix system
has the widest treatment range of any custom laser eye system available
in the United States. Zyoptix LASIK surgery can correct up to -7.00
diopters of nearsightedness (myopia) with up to -3.00 diopters of astigmatism
and "manifest refraction spherical equivalent" equal to or
less than -7.50D. MRSE is a measurement that describes the total refractive
error of the eye.
FRIDAY,
OCTOBER 10, 2003 - Bausch & Lomb has received approval
from the U.S. Food and Drug Administration for its patented, advanced
laser eye surgery system - the Bausch & Lomb Technolas® 217z Zyoptix™
System for Personalized Vision Correction - now making the world’s leading
technology for custom laser eye surgery available in the United States.
Other
Factors to consider
Wavefront-guided
LASIK is not recommended in patients who have diabetes, a history of
Herpes simplex or Herpes zoster keratitis, significant dry eye that
is unresponsive to treatment, or severe allergies. Lower uncorrected
visual acuity may be anticipated in the treatment of higher degrees
of myopia with and without astigmatism. Long-term risks of wavefront-guided
LASIK for myopic astigmatism beyond 12 months have not been studied.
Factors
like corneal thickness and general eye health are important in determining
candidacy. Patients with corneas that are too thin may not be able to
have Wavefront Guided LASIK.
There
is evidence that shows Wavefront Guided LASIK treatments deliver sharper
post-op vision and fewer nighttime side effects than traditional LASIK.
Patients who may benefit greatly from this equipment are those who
have already had LASIK, PRK, or other refractive surgeries and are having
some troubles. Problems such as nighttime glare, halos, quality
of vision issues, and even simply residual refractive error may be eliminated
with the Custom LASIK.
