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Home > Archive > Lasik Eyes Surgery > November 2004 > Enhancement Rates
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| Glenn - USAEyes.org 2004-10-31, 7:11 pm |
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>
>20% is unacceptable and I believe it substantially exceeds the
>labelling (specified in FDA approval documents) indications of
>retreatment rates for myopia or myopia with astigmatism on any
>excimer.
I've reviewed the FDA documents for the original and more recent laser
approvals and there is nothing in them that I can find that indicates
an "approved" enhancement rate. Furthermore, depending upon the
circumstances, a higher enhancement rate may be an indication of a
more conservative surgeon.
The cornea tends to regress back toward the original refractive error
after some refractive surgery procedures. During healing after
refractive surgery, both the corneal epithelium and the deeper stroma
can reshape and reform at different rates and can cause regression.
Regression occurs mostly in myopic (nearsighted) patients who have
more than 6.0 diopters of refractive error and virtually all hyperopic
(farsighted) patients. Regression occurs more commonly with smaller
ablation diameters and with abrupt transition zones at the edge of the
treatment areas. Steroid medications can be used to regulate and
control regression.
A surgeon may deliberately overcorrect the patient to accommodate
expected levels of regression, but this technique runs the risk of
permanent overcorrection if the amount of expected regression is
overestimated. As an example, an 8.00 diopter myope may be
overcorrected to 1.00 diopter of hyperopia with the reasonable
expectation that the hyperopia will regress back to plano (no
refractive error). The problem is that not everyone will respond the
same and that patient who is now a 1.00 D hyperope may not regress at
all and be stuck with hyperopia.
A more conservative doctor may choose to only correct this theoretical
8.00 D myope to plano, allow whatever regression that will occur to
occur, and then enhance the myopia caused by the regression. Since
myopic correction is much more predictable than hyperopic correction,
this technique would provide a higher probability of achieving the
desire outcome without creating a worse situation. This technique
also does not require the extended use of steroids.
Additionally, most providers include enhancement surgery in the cost
of the initial procedure. In other words, it costs them money to
provide an enhancement. Depending upon the specific circumstances, a
high enhancement rate may indicate a surgeon who is willing to accept
additional costs to provide a more conservative technique that may be
better for his or her patients.
It is unwise to use enhancement rates as an indicator of quality of
surgeon or facility, unless you look at all of the circumstances of
each individual patient, surgeon, and facility.
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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| Ragnar Suomi 2004-11-01, 2:09 am |
| You are burying the truth with a load of technical data here. LVI's
20% enhancement rate is due to their high volume, bait-and-switch, pay
extra for enhancement policies. Their surgeons are whores paid to
travel around to up to a dozen facilities sometimes crossing state
lines. They don't even do their own followups, nor could they
considering the volume of patients they do. I wish you would not
offer excuses for LVI's blunders. Anybody who has seen any video of
Marco Musa can tell what a sleazy crook he is. He is a dead-on
example of Ed Begley Jr's portrayal of a filthy rich totally corrupt,
yuppie villain. He even tried to have the police arrest the reporters
doing a story on LVI. He did manage to get the police to fingerprint
the reporters and warn them never to return or they would be arrested.
On Sun, 31 Oct 2004 18:32:27 GMT, Glenn - USAEyes.org
<glenn.hageleSTOPSPAM@USAEyes.org> wrote:
>
>
>I've reviewed the FDA documents for the original and more recent laser
>approvals and there is nothing in them that I can find that indicates
>an "approved" enhancement rate. Furthermore, depending upon the
>circumstances, a higher enhancement rate may be an indication of a
>more conservative surgeon.
>
>The cornea tends to regress back toward the original refractive error
>after some refractive surgery procedures. During healing after
>refractive surgery, both the corneal epithelium and the deeper stroma
>can reshape and reform at different rates and can cause regression.
>
>Regression occurs mostly in myopic (nearsighted) patients who have
>more than 6.0 diopters of refractive error and virtually all hyperopic
>(farsighted) patients. Regression occurs more commonly with smaller
>ablation diameters and with abrupt transition zones at the edge of the
>treatment areas. Steroid medications can be used to regulate and
>control regression.
>
>A surgeon may deliberately overcorrect the patient to accommodate
>expected levels of regression, but this technique runs the risk of
>permanent overcorrection if the amount of expected regression is
>overestimated. As an example, an 8.00 diopter myope may be
>overcorrected to 1.00 diopter of hyperopia with the reasonable
>expectation that the hyperopia will regress back to plano (no
>refractive error). The problem is that not everyone will respond the
>same and that patient who is now a 1.00 D hyperope may not regress at
>all and be stuck with hyperopia.
>
>A more conservative doctor may choose to only correct this theoretical
>8.00 D myope to plano, allow whatever regression that will occur to
>occur, and then enhance the myopia caused by the regression. Since
>myopic correction is much more predictable than hyperopic correction,
>this technique would provide a higher probability of achieving the
>desire outcome without creating a worse situation. This technique
>also does not require the extended use of steroids.
>
>Additionally, most providers include enhancement surgery in the cost
>of the initial procedure. In other words, it costs them money to
>provide an enhancement. Depending upon the specific circumstances, a
>high enhancement rate may indicate a surgeon who is willing to accept
>additional costs to provide a more conservative technique that may be
>better for his or her patients.
>
>It is unwise to use enhancement rates as an indicator of quality of
>surgeon or facility, unless you look at all of the circumstances of
>each individual patient, surgeon, and facility.
>
>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.
| |
| Rebecca 2004-11-04, 7:16 pm |
| Glenn - USAEyes.org <glenn.hageleSTOPSPAM@USAEyes.org> wrote in message news:<gqaao05qerl72bgt0g0tf8amjvfuiqpfkc@4ax.com>...
> I've reviewed the FDA documents for the original and more recent laser
> approvals and there is nothing in them that I can find that indicates
> an "approved" enhancement rate. Furthermore, depending upon the
> circumstances, a higher enhancement rate may be an indication of a
> more conservative surgeon....
>
> ...A more conservative doctor may choose to only correct this theoretical
> 8.00 D myope to plano, allow whatever regression that will occur to
> occur, and then enhance the myopia caused by the regression....
> ...Depending upon the specific circumstances, a
> high enhancement rate may indicate a surgeon who is willing to accept
> additional costs to provide a more conservative technique that may be
> better for his or her patients.
>
> It is unwise to use enhancement rates as an indicator of quality of
> surgeon or facility, unless you look at all of the circumstances of
> each individual patient, surgeon, and facility.
Glenn,
Having looked into the medical and regulatory implications of very
high retreatment rates extensively, I find that the inevitable
conclusion is that enhancement rates are very significant safety and
efficacy indicators, and that both doctors and the FDA seem to agree
about this. I will explain. And I need to make it clear up front that
I am not writing this to demonstrate that a surgeon with a high
retreatment rate is a "bad surgeon". The surgeon is only one factor in
the equation.
I am going to start with the medical implications and because this
will be quite long, I will address the regulatory issues later in a
separate post.
It is indisputable that retreatments, which are second surgeries,
expose patients to additional risk. This is not desireable. A high
retreatment rate, even if it could be explained by the example you
have cited (and I will address that probability in a minute) of
deliberately undercorrecting some patients, cannot if occurring
routinely be viewed as a sign of conservative medical practice in that
it exposes the patient not only to the general risks of two corneal
surgeries rather than one, but to the unique risks posed by secondary
ablation and by flap lifts.
The practical reality of LASIK is that doctors have learning curves
and since each doctor operates in a unique environment, nomograms are
adjusted over time. Therefore, intuitively, retreatment rates decrease
over time. Assuming a competent, properly trained surgeon who is
following all instructions and incorporating experience into his
practice, a sustained high retreatment rate must point to the device.
With respect to retreatment rates varying by type of patient, it is
well known that the different types of correction (low, moderate and
high myopia, hyperopia, mixed astigmatism, etc) have different
retreatment rates associated with them. This is also clear in the
product labelling prescribed during the device approval process. If we
want to understand the average retreatment rates of a medium to high
volume surgeon, we have to look at the average number in context. The
bread and butter of his practice is the low to moderate myopes, who
represent the vast majority of the consumer pie, rather than, say, the
very high myopes or hyperopes who will always be a small minority of
individuals eligible for LASIK.
A 20% overall retreatment rate is highly unlikely to be explainable by
the deliberate undercorrection theory (other than possibly in a very
low-volume situation) even supposing an extreme case where the surgeon
in question ALWAYS adopts such an approach and then ALWAYS sees a need
for and recommends a retreatment and the patient is ALWAYS eligible
and ALWAYS agrees to undergo a retreatment, simply becaues very high
myopes constitute such a small minority of the patients. Ditto for
other unusual refractive errors which, assuming a target of plano
(zero prescription), are simply by their nature more likely to result
in an under- or overcorrection.
But it is the conventional, not the extreme, clinical practices that
are of the most interest to the LASIK consumer. Generalisations about
retreatments need to be at least reasonably applicable to the average
surgeon. Let's move on therefore in discussion to the typical medium
to high volume surgeon and question whether unusual refractive error
cases and/or deliberate undercorrection can account for a SUSTAINED
(say over a period of a year or more) 20% retreatment rate. Now, the
statistically unlikely becomes closer and closer to statistically
impossible as the sample size becomes larger and more closely
resembles the population averages ("population" herein understood to
be that of people deemed eligible for LASIK).
Then throw in all the other "possible" explanations of individual
under/overcorrections and you are still moving that average by only a
tiny amount in percentage terms if you are looking at data over a
significant period of time. Suppose for example the discount clinic
down the street goes out of business and you get a temporary influx of
patients requiring retreatment. Unless it was an extremely high volume
clinic and there is no other surgeon within 50 miles, this too may
temporarily boost the numbers but it's not going to send your annual
figures skyrocketing.
The key point here is that there are many POSSIBLE explanations for
INDIVIDUAL under/overcorrections or even short-lived "clusters" of
them. But the combinations of events which would have had to take
place to result in a 20% or greater retreatment rate, again assuming a
reasonably competent, trained, medium to high volume surgeon, and
properly functioning equipment, are not even remotely plausible enough
to be used to say that 20% is, in general, a number that can be
explained by XYZ.
So what IS a normal and/or acceptable retreatment rate?
(And let's bear in mind here that a retreatment rate in any mainstream
practice would normally represent a number SMALLER than the actual
rate of overcorrections, undercorrections and regression occurring
over a given period of time, because, among other things, not all
patients will be eligible and/or willing to undergo further treatment,
and furthermore the amount of correction has to be large enough to
make more surgery worth the risk, as was agreed by various
participants in a recent thread on this NG.)
There are at least two ways to answer this question:
Acceptable retreatment rates (from a medical standpoint) may be
described as what doctors believe to be acceptable (i.e. looking at it
from a "standard of care" perspective)
And,
Acceptable retreatment rates (for purposes of determining acceptable
device performance) may be described as what the FDA believes is
acceptable (as mentioned, I will be covering this in a bit).
So what do doctors believe to be acceptable?
1) Financially, a retreatment rate higher than 10% (or, in many cases,
considerably lower, depending on the assumptions in the business plan,
which may or may not have built in a margin for error above what the
clinical trial results were) may well impose a significant hardship on
the surgeon/clinic due to increased chair time and royalty payments.
That, coupled with the increased risk (and incidence) of complications
and decreased patient satisfaction, creates a substantial incentive to
surgeons to keep retreatment rates low.
2) Anecdotally, patients and journalists who have asked this question
at clinics are typically given a number that is between 2% and 10%,
most falling into the 5-8% range. Also anecdotally, the only surgeons
of my acquaintance who have ever acknowledged to me an average
retreatment rate of higher than 10% expressed dissatisfaction with
that rate and had sought explanations and redress from the
manufacturer, in some cases successfully (eg changes to software or
the maintenance programme were implemented, or the machine was
replaced) and in other cases not so the surgeon went and acquired a
different laser and is now much happier.
3) MarketScope's annual surveys, which technically would also fall
into or somewhere near the "anecdotal" category as they are simply
surveys of surgeons' opinions about their practice and are
self-selecting, consistently indicate average retreatment rates in the
5 to 8% range (6.8% in the June 2003 survey, with actual numbers in a
fairly tight range according to a conversation with Dave Harmon). So
what does that mean? Well, if we take the most optimistic view (that
participating surgeons represent a good cross-section of users of all
different lasers and that all surgeons answered that question and
answered it with precision), then MarketScope's retreatment rates ARE
the norm. On the other hand if we take the most cynical view, that
doctors with high rates withheld information or provided wrong
information or participation was somehow weighted towards lasers which
have lower retreatment rates than others, MarketScope's retreatment
rates are what SURGEONS BELIEVE to be the norm or to be acceptable.
It's either one or the other. There's no escaping it.
On the other hand, if reputable surgeons were to raise their hands and
say "Gee, you're wrong, we think a sustained retreatment rate of 20%
or more is just peachy keen, and if ours were 20% it wouldn't bother
us a bit", that would no doubt alter the picture.
But I don't think they will. First, because I believe consumers,
tolerant though they generally seem to be, would object to being given
a one in five chance of needing two surgeries rather than one.
Secondly, because of the regulatory implications, which I will address
shortly.
In fact, I agree with Ragnar (I know, I know who woulda thunk it?) who
posted about a week ago that "nobody else has much higher than an 11%
rate and a good surgeon will have about 3%" - though I might even give
the "good surgeons" a teensy bit more leeway than this.
Rebecca Petris
www.lasermyeye.org
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| Glenn - USAEyes.org 2004-11-04, 7:16 pm |
| A truly great post of well reasoned and comprehensive thought. You
have covered many of the important issues surrounding retreatment
rates. There are a few additional points I'd like to address.
My example relates to an individual surgeon who may use what some
might consider a more conservative approach to correction of high
refractive errors. I am not suggesting that this philosophy is
universally accepted by all refractive surgeons, but am presenting a
real situation where an individual surgeon's enhancement rates may
seem much higher than the norm, but not because the doctor is a "bad"
surgeon.
An opposite example of one of the factors that dramatically affects
retreatment rates is a clinic's business policy. A few clinics I have
run into have a policy that they will not enhance a patient who has
20/40 or better uncorrected vision. That clinic would factually
report a very low enhancement rate and you may even decide that
surgeon is a "good" surgeon because of this low enhancement rate, but
upon reflection the enhancement rate is falsely less than the norm
because of an unusual business decision.
The doctor's current enhancement rate is included as one of our 50
Tough Questions For Your Doctor
(http://www.usaeyes.org/faq/tough_questions.htm), but we also make it
clear that one must understand the doctor's enhancement policy and
that this is only one of 50 important questions.
As you mentioned, the learning curve creates a unique circumstance
where enhancement rates may go off the board, and everyone needs to
understand that there is a learning curve with EVERY new piece of
equipment and EVERY new technique and even with staff changes. I've
seen doctors go from one laser to a different version of the same
laser and have clinically significant different results. The same is
true with microkeratomes, going from LASIK to PRK, different
technicians, etc. This is why in our 50 Tough Questions For Your
Doctor we have the question of how many surgeries of exactly the same
technique, equipment, even staff has the doctor performed. Small
changes can make important differences.
As you know, Rebecca, there are currently two US lawsuits that claim a
laser manufacturer delivered an inferior product because the two
groups of surgeons had unexpected results (primarily undercorrection)
and a high number of enhancements. The fact that other doctors who
were delivered the same models at the same time did not have these
results, and that these claims of laser inferiority were not made
until the manufacturer sued these groups for collection of royalty
fees in the millions of dollars may have something to do with these
claims, but they illustrate that practical knowledge with consistency
is a valuable asset to a patient evaluating a potential surgeon.
None of these examples either excuse or justify a surgeon having a
particular retreatment rate. You have used 20% in your example and
that does seem to be more than twice what most surgeons report as the
high end of the norm after algorithms and nomograms have been
adjusted. In our 50 Tough Questions we suggest that anything over 10%
needs additional consideration. The point of my examples is that
retreatment rates alone are not necessarily a reliable indication of a
surgeon's quality because there are so many variables that can grossly
affect the rates that do not necessarily relate to the quality of the
surgeon.
I look forward to your promised post regarding the FDA's position on
retreatment rates.
One last point: Many of the outcomes reports from surgeons ARE
anecdotal and ARE what the doctors THINK they do. I know first-hand
that actual results when you look at the hard data is not always the
perception the doctor has of his or her outcomes.
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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