Hello Art. I hope I can be of assistance.
Like nearly all new technology, there are advantages and
disadvantages. What one must do is determine if the advantages
outweigh the disadvantages. It is my opinion that the advantages of
the Intralase femtosecond laser for creation of the LASIK flap
(IntraLASIK) outweigh the disadvantages, but you must come to your own
conclusion.
The primary advantage of IntraLASIK is accuracy of flap depth and
safety. The primary disadvantage of IntraLASIK is short-term swelling
and a higher probability of a longer healing time before good visual
acuity (weeks instead of days). IntraLASIK is also usually more
expensive.
IntraLASIK is accurate within about 10 microns. A mechanical
microkeratome is usually accurate within 30-50 microns, but there are
case studies of mechanical microkeratomes being off by 150 microns and
more. This is important because at least 250 microns of cornea must
remain untouched to provide stability after surgery, and the average
cornea is around 500 microns thick. Unless you have 150 microns to
spare, there is a slightly higher element of risk with a mechanical
microkeratome. I want to be quick to add that these large variables
are very, very rare, but do occur.
It is virtually impossible to create a buttonhole flap with
IntraLASIK. That is when the microkeratome pass is too shallow and
the blade breaks through the surface in the middle of the flap.
Buttonhole flaps are normally not very problematic. The doctor
repositions the flap, waits about three months, then does the
procedure again. Of course, nobody wants a buttonhole flap, no matter
how well they heal.
If for any reason the IntraLASIK flap is aborted during the process,
such as suction loss, it can be continued later at exactly the same
depth without causing vision problems. If a mechanical microkeratome
aborts during flap creation, there is a risk of ridge formation and a
second flap would need to be created at a different depth. It is
nearly impossible to complete later an aborted LASIK flap made with a
mechanical microkeratome.
The IntraLASIK flap is an even thickness throughout. Think of it like
a man-hole cover with edges that go straight up. A flap created with
a mechanical microkeratome is meniscus shaped with thin edges, thick
mid-periphery, and a slightly thinner center. It is believed, but not
really proven, that the uniform flap provides uniform internal
stresses and therefor is less likely to create the tiny crinkles in
the flap called micro-striaie. With all microkeratomes, micro-striae
is quite rare, but can occur and is difficult to resolve through means
other than healing.
Intralase causes a series of "explosions" along a predetermined plane
within the cornea. These explosions create tiny pockets of gas. With
enough explosions close enough together, a flap is created. Because
the flap is created by a series of bubbles, the IntraLASIK flap is not
quite as smooth as a flap made with a mechanical blade. A smoother
flap is a better flap.
It is surmised that these explosions cause slight swelling that takes
several days to a few weeks to settle down. During this time, the
patient will have less than clear vision. Also, it is surmised that
the relative roughness of the IntraLASIK flap provides less clear
vision during the healing time. What I have seen is that after the
normal healing process this problem resolves completely in virtually
all patients.
Practical experience is important for any doctor who implements a new
technology. Some technologies and techniques require much more
surgical skill than others. Some have a faster learning curve than
others. In our 50 Tough Questions For Your Doctor, we recommend that
a doctor have performed at least 100 of the procedures proposed for
you. That may be a bit restrictive for IntraLASIK, but in a few
months, 100 is probably easily accomplished by a higher volume
surgeon.
So to summarize, IntraLASIK seems to be more accurate and somewhat
safer long-term, but you will put up with less than optimum vision
quality for a few weeks to a few months while the cornea heals.
And your wallet will be a bit lighter with IntraLASIK.
Best of luck with your decision.
Glenn Hagele
Executive Director
Council for Refractive Surgery Quality Assurance
Email to glenn dot hagele at usaeyes dot org
http://www.USAeyes.org
http://www.ComplicatedEyes.org
I am not a doctor.
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