Types of lasers
KC
thoughts on what's the best choice?
Thanks
-KC
Ragnar Suomi
Price is one consideration. Don't go for the lowest price. The eyes
are less forgiving than even the brain or heart in surgery. You
wouldn't go to a discount brain or heart surgeon (without making your
will out first).
Most important is to take a tour of the facility you intend on having
your surgery. I nearly had surgery done at a place I had never been
to before the day of surgery. That place was a supermarket of
surgery. If your surgeon can't spare 5 minutes to talk to you ALONE,
then just walk out. Some places will not let you talk to the
surgeon.
Oh, and ask how often the surgeon is in THAT office. If it's less
than 3 days a week, go someplace else. There are places where the
surgeon is only there one day every 3 weeks.
Glenn Hagele - Council for Refractive Surgery Quality Assurance
For more information about the best laser, visit
http://www.usaeyes.org/faq/subjects/which_laser.htm
Glenn Hagele
Executive Director
Council for Refractive Surgery Quality Assurance
http://www.USAeyes.org
http://www.ComplicatedEyes.org
glenn dot hagele at usaeyes dot org
I am not a doctor.
lasik advocate with flap melt
than the oldest technology being used out there? Even I find this
hard to believe. Aren't both important?
> The laser used is much less important than the doctor's proven abilities.
Glenn Hagele - Council for Refractive Surgery Quality Assurance <glenn.hage...@USAeyes.org> wrote in message news:<g5k1mvgknogn435i9...@4ax.com>...
Tom
surgeon now uses a MEL 80 (in Canada). Or the Allegretto Wavelight?
Arguably superior equipment to that of the FDA approved lasers - been used
internationally a lot more than some of the obsolete equipment in the
States. It's a possible option for those willing to travel outside of the
US.
"Glenn Hagele - Council for Refractive Surgery Quality Assurance"
<glenn.hage...@USAeyes.org> wrote in message
news:g5k1mvgknogn435i9...@4ax.com...
Glenn Hagele - Council for Refractive Surgery Quality Assurance
difference and that difference is defined.
Glenn Hagele - Council for Refractive Surgery Quality Assurance
>What about non-FDA approved lasers. I had my surgery with a MEL 70 - my
>surgeon now uses a MEL 80 (in Canada). Or the Allegretto Wavelight?
>Arguably superior equipment to that of the FDA approved lasers - been used
>internationally a lot more than some of the obsolete equipment in the
>States. It's a possible option for those willing to travel outside of the
>US.
>
You are very correct about some non-US lasers. The Mel-70 and Mel-80
are true flying spot lasers. The Allegretto is a flying spot but has
the added advantage of software that keeps the cornea more prolate in
shape than the oblate shape created with most lasers.
For some patients this level of technology is a requirement. For
others, it is an option.
lasik advocate with flap melt
results on average are comparable to any other laser then? All lasers
get similar results for some patients?
Glenn Hagele - Council for Refractive Surgery Quality Assurance <glenn.hage...@USAeyes.org> wrote in message news:<qep2mv454s5eip3sf...@4ax.com>...
Glenn Hagele - Council for Refractive Surgery Quality Assurance
with flap melt) wrote:
>Are you saying that for those patients where it's an "option", the
>results on average are comparable to any other laser then? All lasers
>get similar results for some patients?
Yes, for some patients the results are essentially the same. For
others the higher level technology is required to achieve an optimum
outcome. For all, the highest level of technology is an option, but
not necessarily a requirement.
The trick, of course, is knowing who is which.
lasik advocate with flap melt
Since you have access to the medical records of the CRSQA surgeons, I
think we'd all like to know about their results on average. You've
indicated that they have somewhat less than 3% complications and ~.5%
"catastrophic" complications. Are you saying that these surgeons have
1 in 200 patients who result in injuries to their eyes equivalent to
"Catastrophic Injury: sport injury that resulted in a brain or spinal
cord injury or skull or spinal fracture. "?
http://www.unc.edu/depts/nccsi/InjuryTerms.htm
Do you believe that ". . .the purpose of myopic refractive surgery…to
flatten the central part of the cornea."?
How many people who have refractive eye surgery (LASIK or PRK/LASEK)
intended to NOT keep the cornea prolate have MORE higher order
aberrations after the surgery than they did before it? 50%, 75%,
100%??? How many have LESS afterwards?
How many people who have refractive eye surgery (LASIK or PRK/LASEK)
designed to keep the cornea prolate have MORE higher order aberrations
after the surgery than they did before it? 10%, 20%, 30%??? How many
have LESS afterwards?
What sane person wouldn't choose superior vision if all other factors
were equal?
Are these 2 statements consistent?
A. As I stated before, a prolate cornea may provide superior vision
over an oblate cornea, but this very small change may be less
important to someone who cannot see four inches in front of them
without glasses.
B. For all, the highest level of technology is an option, but not
necessarily a requirement.
Do you mean that for some people superior vision isn't necessary even
if the technology is available to offer this to them? Why would
someone knowing choose inferior vision? Do the CRSQA Doctors include
this in the informed consent for all patients who do NOT receive
prolate corneas even though the technology is readily available? Are
they told they will receive "inferior" vision that is a "very small
change" and may or may not be "less important" to them? What if it IS
important to them and they are NEVER given a choice? What if they
would gladly pay an extra $5,000 or whatever it costs for a more
natural prolate cornea shape, and they are NOT told that this laser or
this Doctor doesn't even offer this readily available option?
The question was if the cornea was
flattened and that is the purpose of myopic refractive surgery…to
flatten the central part of the cornea.
That is not to
say that an oblate cornea does not provide excellent vision, it is
just that the prolate cornea may provide superior vision.
Based upon
clinical evaluations and the millions of people who are ecstatic about
their refractive surgery, it appears that it is not too negatively
affected.
As I stated before, a
prolate cornea may provide superior vision over an oblate cornea, but
this very small change may be less important to someone who cannot see
four inches in front of them without glasses.
Someone with thin corneas,
low contrast sensitivity, history of eye disease, dry eyes, or many
other conditions may be excluded from refractive surgery. That is why
it is so important to be evaluated by a competent surgeon.
http://groups.google.com/groups?q=prolate+group:alt.lasik-eyes&hl=en&lr=&ie=UTF-8&group=alt.lasik-eyes&safe=off&selm=3d8a1b14.65364444%40news.concentric.net&rnum=4
bryca...@socal.rr.com (Bryce Carlson) wrote in message news:<14e1a0fe.03081...@posting.google.com>...
> Here's a little primer on RS and GASH:
>
> GASH is certainly related to the delta between scotopic pupil diameter
> and optical zone (OZ) diameter, but the correlation is not one to one.
> Below are some of the known operative variables and their relative
> importance.
>
> (1) Even with an optical zone (OZ) as large as or larger than the
> scotopic pupil size, GASH can still occur because of a programming
> error common to all excimer lasers used for RS, except the Meditec
> Mel-70/80. Excimer lasers used for RS (except the Mel-70/80) wrongly
> assume that the goal for myopic correction is to take a hemisphere
> with a smaller radius and turn it into a hemisphere with a larger
> radius. This is not quite right. The normal emmetropic cornea is not
> spherical; it's prolate. This means that it is steeper in the center
> (say, central 3 mm, or so), and flatter towards the periphery. This
> prolate geometry allows all the rays entering the eye (not just those
> that enter at the center) to focus properly on the retina. By
> creating a spherical (or, worse yet, oblate) shaped cornea, RS
> guarantees that the light entering the cornea from the periphery will
> not quite focus properly on the retina (peripheral myopia). The
> degree of myopic distortion is largely a function of how much
> correction is burned into the cornea with the ablation. Mild
> corrections (say, 2 D, or less) often result in little to no
> noticeable GASH. Large corrections (say, 7 D, or more) often result
> in a lot of noticeable GASH. Intermediate corrections often result in
> moderate GASH. The reason this programming error was built into RS
> lasers is because it is difficult to properly program prolate
> ablations, it requires better registration than was previously
> available, and it also requires a deeper ablation. As the importance
> of this factor has become apparent, however, it is likely that most of
> the laser manufacturers (VISX, Autonomous, B & L, etc.) will update
> their software to allow for prolate ablations.
>
> (2) Even with a deep, too small spherical/oblate ablation, however,
> some people do not get noticeable GASH. This can be due to simple
> cognitive filtering, but it may also be due in part to the
> Stiles-Crawford effect. The Stiles-Crawford effect is a known effect
> in optical physics that says that refracted light entering the eye at
> the periphery loses energy compared to (relatively) unrefracted light
> entering near the center. This means that the lower-energy peripheral
> light has less optical effect (is noticed less) than the higher-energy
> central light. So, some people may have mild peripheral blur (GASH)
> but it's too dim to be really noticed.
>
> (3) Even with an optical zone (OZ) as large as or larger than the
> scotopic pupil size, GASH can still occur if the patient is slightly
> undercorrected. Undercorrections of as little as -0.5 D, or so, can
> result in noticeable dim-light peripheral blur (GASH).
>
> (4) Of course, the most common cause is an OZ ablation diameter that
> is less than the scotopic pupil diameter. This can occur for a
> variety of reasons, including ablation decentration, mismeasurement of
> the scotopic pupil size, inappropriately considering the total
> ablation size (OZ plus BZ) rather than just the OZ, etc.
>
> So, these are some of the operative factors, and you can see that the
> physics of GASH is more complicated than you might think at first
> glance.
>
> Bryce Carlson, PhD
kpat...@hotmail.com (lasik advocate with flap melt) wrote in message news:<b0866067.03081...@posting.google.com>...
> 1. With LASIK, the shape of the eye is permanently changed from
> concave to convex- it's well documented.
>
> "We are actually ruining the optics of the eye when we perform LASIK,"
> . . ."That's fine when the pupil is small, but as it gets larger, such
> as in nighttime conditions, this becomes a problem. For the last five
> years, I have been preaching that we should not be doing this."
> (http://jordan.fortwayne.com/ns/projects/lasik/lasik5.php).
>
> "We need to think in detail about corneal optics after refractive
> surgery because the normal cornea is relatively trouble-free. The
> cornea after refractive surgery is not trouble-free. It frequently
> has a more aberrated optical performance than its preoperative
> counterpart. (Dr. Leo J. Maguire, Keratorefractive Surgery, Success,
> and the Public Health, Am. J. Ophth., Vol. 117, No. 3, 3/94).
>
> Is the Public informed that eye surgery causes increased higher order
> aberrations and what happens when the cornea shape changes from the
> way it evolved over millions of years (concave) to a more flattened
> convex shape? "There is not a single laser on the US market today
> that delivers the appropriate overall energy for the ablations we
> perform". "Our data show that the lasers are actually undertreating in
> the periphery?at 6.0 mm, it is about 25% reduced from its designated
> calculation?and in doing so, they make the cornea more oblate, rather
> than preserve its natural prolate shape"
> (http://www.crstoday.com/02_current/crst0103_11.html). "Conventional
> laser surgery typically treats the central portion of the eye"
> (http://www.stanfordhospital.com/newsEvents/newsReleases/2002/052002/correctVision.html).
>
> Vision quality is usually Not as good afterwards as it was before when
> corrected with glasses or contacts. "The problem with all excimer
> lasers on the market today is twofold. First, the engineers assumed
> that the cornea is spherical rather than prolate. Second, they
> assumed that their job was to reshape a relatively steep sphere into a
> relatively flat sphere, rather than to reshape a steep prolate into a
> flatter prolate. As a result, excimer lasers actually reshape prolate
> corneas into what is known as oblate?This shape is actually optically
> worse than a sphere, because now the peripheral rays are bent even
> more powerfully than in the periphery of a sphere, causing even more
> pronounced spherical aberration when the pupil dilates?This problem
> affects every patient who undergoes an excimer laser procedure to some
> extent." (What We Should Really Tell LASIK Patients, Rev. Ophth.,
> 5/99).
>
> "The newly formed corneal surface is often irregularly aspheric,
> probably the cumulative results of imperfect surgery, equipment, and
> unpredictable healing." "Central processing of the visual image in
> the brain is able to pull out the sharp image from the surrounding
> blurred images. However, the limit of resolution of such a process is
> probably not better than 20/40 if the emmetropic corneal area is
> small. I think that the asphericity effect is not only due to a
> variable corneal surface but also due to fluctuations in refractive
> index in the subepithelial and/or superficial stroma (ie., the little
> island lenses)." (http://jrs.slackinc.com/vol142/bkrev.pdf).
>
> Glare, Halos, Starbursts, diplopia and other vision problems
> (including in ordinary indoor lighting conditions) are more common in
> other studies done than in those used for the PMA approvals
> (http://jrs.slackinc.com/vol142s/abs-l.pdf).
>
> 2. Is LASIK safe?
> Some eye surgery causes a permanent wound (a flap) that never heals.
> "The most common cause of an incomplete pass is mechanical
> interference by the lids, speculum, or drapes."
> (http://jrs.slackinc.com/vol162s/Gim2.pdf). "LASIK has a unique
> safety issue not present with other refractive surgical procedures,
> which stems from the structural weakness of the corneal flap and its
> poor adhesion to the underlying corneal stroma. In some ways it is
> remarkable that the flap can "reattach" so easily without sutures.". .
> ."There is also the problem of accurately realigning the flap and
> replacing it in the correct location. Flap decentration has been
> reported. As with flap wrinkling, it will lead to reduced optical
> quality." (http://www.opt.indiana.edu/IndJOpt/download/ijosum00.pdf).
>
> 3. What happens to the cornea and the eye after Elective Refractive
> Eye Surgery is Not healthy
> (http://www.audio-digest.org/pages/htmlos/0244.35.3746433717410210490/OP4102;
> http://www.icare4u.com/surgery.htm).
Glenn Hagele - Council for Refractive Surgery Quality Assurance <glenn.hage...@USAeyes.org> wrote in message news:<van4mvg35fm44f5ag...@4ax.com>...
Glenn Hagele - Council for Refractive Surgery Quality Assurance
with flap melt) wrote:
CRSQA surgeons must meet or exceed the national norms, therefore it is
obvious that their outcomes are better than the average. Exactly how
much better we do not publish because we do not want to promote the
idea that a patient can expect better than the norm. If someone
expects better than the norm, that is an unreasonable expectation.
>
>Do you believe that ". . .the purpose of myopic refractive surgery…to
>flatten the central part of the cornea."?
The process of LASIK, LASEK, PRK, LASEK, and Intacs is to flatten the
central part of the cornea, causing a change in the refractive error.
>How many people who have refractive eye surgery (LASIK or PRK/LASEK)
>intended to NOT keep the cornea prolate have MORE higher order
>aberrations after the surgery than they did before it? 50%, 75%,
>100%??? How many have LESS afterwards?
Unknown.
>
>How many people who have refractive eye surgery (LASIK or PRK/LASEK)
>designed to keep the cornea prolate have MORE higher order aberrations
>after the surgery than they did before it? 10%, 20%, 30%??? How many
>have LESS afterwards?
Unknown.
>
>What sane person wouldn't choose superior vision if all other factors
>were equal?
Superior is NOT a choice, it is a target. Whether or not it actually
occurs is difficult to predict. One can only increase the
probability, not guarantee the result. If the techniques and
technology that would increase the odds of superior vision are not
available, a person may decide to seek normal vision.
>
>Are these 2 statements consistent?
>A. As I stated before, a prolate cornea may provide superior vision
>over an oblate cornea, but this very small change may be less
>important to someone who cannot see four inches in front of them
>without glasses.
>B. For all, the highest level of technology is an option, but not
>necessarily a requirement.
In a general sense, they seem to be.
>
>Do you mean that for some people superior vision isn't necessary even
>if the technology is available to offer this to them? Why would
>someone knowing choose inferior vision?
I don't think anyone considers normal unaberrated 20/20 vision as
"inferior".
>Do the CRSQA Doctors include
>this in the informed consent for all patients who do NOT receive
>prolate corneas even though the technology is readily available?
All doctors discuss with their patients what can be reasonably
expected as an outcome, and the possible negative possibilities. A
good doctor understands the limitations of his or her techniques and
technologies. It is the patient's decision if what is being offered
as a probability is acceptable.
>Are
>they told they will receive "inferior" vision that is a "very small
>change" and may or may not be "less important" to them?
As I have stated, the doctor will discuss what outcome is probable and
perfect vision is not inferior.
>What if it IS
>important to them and they are NEVER given a choice?
The patient always has the choice to not have surgery.
>What if they
>would gladly pay an extra $5,000 or whatever it costs for a more
>natural prolate cornea shape, and they are NOT told that this laser or
>this Doctor doesn't even offer this readily available option?
The patient needs to decide if what is being offered is acceptable,
then proceed with that option. If it is not acceptable, then the
patient should NOT have surgery. If a patient requires better than
perfect vision, that patient should NOT have refractive surgery no
matter what the technique or technology.
lasik advocate with flap melt
keeps the cornea prolate with LASIK that flattens the cornea- both are
available now. Doesn't flattening the cornea have a high likelihood
(virtually guarantee depending on prescription) an increase in higher
order aberrations, and isn't there a reasonable chance that leaving
the cornea prolate will NOT increase the higher order aberrations? On
average, isn't vision superior (using your word) with the wavefront
guided prolate procedure than with the older flattening technologies?
On the surface, your answers seem reasonable for a layperson, but you
are in charge of certifying Doctors and you didn't answer the
questions I asked. Shouldn't this be part of your 50 (or more) tough
questions if it's important for patients to know before surgery?
First of all, you have indicated that ALL complications are evaluated
by CRSQA. Are you saying that increased higher order aberrations
after surgery compared to pre-op are NOT considered a complication at
all?
Secondly, you wrote previously that some laser technology is available
that does NOT flatten the cornea- rather it keeps the original prolate
shape. Keeping the prolate shape means that the higher order
aberrations are NOT necessarily increased by the surgery. You
referred to this as superior vision. What sane person would prefer a
procedure with a higher chance of creating inferior vision over
another procedure? If you don't know, then why don't you ask your
Doctors and post an answer? If they don't know, then why are they
using these procedures? How do they pick one laser or one procedure
over another?
Thirdly, you have written that you don't monitor what your doctors say
to patients. If they are NOT using the superior technology, Do you
think they tell their patients that there is a superior technology
available? If you don't know, then why don't you ask them?
Are you just being deliberately vague? Do CRSQA Doctors answer their
patients questions this way? Rather than providing an answer, they
answer different questions? When did you have surgery? How's your
vision?
Glenn Hagele - Council for Refractive Surgery Quality Assurance <glenn.hage...@USAeyes.org> wrote in message news:<ibjbmv8a6q97h1ccl...@4ax.com>...
> On 14 Sep 2003 16:01:18 -0700, kpat...@hotmail.com (lasik advocate
> with flap melt) wrote:
>
> >Glenn,
> >
> >Since you have access to the medical records of the CRSQA surgeons, I
> >think we'd all like to know about their results on average.
>
> CRSQA surgeons must meet or exceed the national norms, therefore it is
> obvious that their outcomes are better than the average. Exactly how
> much better we do not publish because we do not want to promote the
> idea that a patient can expect better than the norm. If someone
> expects better than the norm, that is an unreasonable expectation.
> >
> >Do you believe that ". . .the purpose of myopic refractive surgery?to
lasik advocate with flap melt
"normal" vision? Is that what you meant?
Glenn Hagele - Council for Refractive Surgery Quality Assurance
with flap melt) wrote:
>Do you consider increased higher order due to a flattened cornea
>"normal" vision? Is that what you meant?
Are you joking or just trying to be argumentative? Vision that is in
all regards equal or similar to those standards that in the last
several hundred years have been determined to represent normal vision.
Normal vision has been acheived by millions who have attained an
oblate (well, more oblate anyway) corneas.
Glenn Hagele - Council for Refractive Surgery Quality Assurance
>Who said anything about perfect vision?
You did.
>I was comparing LASIK that
>keeps the cornea prolate with LASIK that flattens the cornea- both are
>available now.
So what, exactly, is your comparison/question?
> Doesn't flattening the cornea have a high likelihood
>(virtually guarantee depending on prescription) an increase in higher
>order aberrations, and isn't there a reasonable chance that leaving
>the cornea prolate will NOT increase the higher order aberrations?
"(H)igh likelihood"? No. Greater likelihood in certain circumstances?
possibly. Jack Holladay, MD has done a lot of work on forwarding this
consideration.
>On
>average, isn't vision superior (using your word) with the wavefront
>guided prolate procedure than with the older flattening technologies?
I'm assuming you meant to say "better than".
To my knowledge, there are no studies or even anecdotal reports that
wavefront-guided ablations have been compared with a more prolate
cornea compared to a less prolate cornea. The current excimer laser
system that has software to maintain a more prolate shape is not
wavefront-guided. I could be wrong, but I've seen nothing on this
issue. Nothing at all.
Further, the oblate - prolate issue is moot if the wavefront-guided
technology is able to reduce or eliminate the Low Order Aberrations
(LOA) and first four Zernike levels of High Order Aberrations (HOA).
Arguing about prolate v. oblate is like debating the number of angles
on the head of a pin if the surgery consistently and predictably
provides excellent results.
>
>On the surface, your answers seem reasonable for a layperson, but you
>are in charge of certifying Doctors and you didn't answer the
>questions I asked. Shouldn't this be part of your 50 (or more) tough
>questions if it's important for patients to know before surgery?
Perhaps you simply do not understand my responses, or I did not
understand your statements and questions to which I responded.
>
>First of all, you have indicated that ALL complications are evaluated
>by CRSQA. Are you saying that increased higher order aberrations
>after surgery compared to pre-op are NOT considered a complication at
>all?
You are attempting to create a complication where a complication does
(or may) not exist. An increase in HOA does not automatically cause a
vision aberration. In fact at a recent meeting it was demonstrated
that a slight increase in particular HOAs can actually improve vision
quality. A change in HOA is not, per se, a complication. A vision
aberration reportable by the patient, such as halos, starbursts, etc.,
is a complication. It may be determined which HOA can reduce or
eliminate this complication by its reduction, but a change in HOA does
not in itself constitute a complication.
Let me put it another way. There are people with perfectly functional
non-aberrated vision who have never had refractive surgery who have
HOAs higher that people who have had refractive surgery who complain
of a complication that is directly measurable by a particular HOA.
The person with the high HOA, but no vision problem, does NOT have a
complication.
All studies are subject to inclusion in our Quality Standards Advisory
Committee's evaluation and determination of the current national norms
for refractive surgery outcomes. Wavefront diagnostic is able to
provide explanations for some problems that heretofore were
unexplainable.
>
>Secondly, you wrote previously that some laser technology is available
>that does NOT flatten the cornea- rather it keeps the original prolate
>shape.
Both your suggestion that I said this and the idea that some laser
technology does not flatten the cornea to change the refractive error
to reduce myopia are not true. All excimer laser assisted techniques
flatten the cornea centrally to achieve myopic correction...some more
than others.
>Keeping the prolate shape means that the higher order
>aberrations are NOT necessarily increased by the surgery.
This is an overly simplistic view that is not fully accurate. You
seem to have latched onto a concept as if it is a panacea, which it is
not. HOAs can increase with or without a more prolate shape.
> You
>referred to this as superior vision.
Again, you have apparently not understood my statements. Superior
vision is vision that is greater than the norm. An example would be
unaberrated 20/15 vision.
>What sane person would prefer a
>procedure with a higher chance of creating inferior vision over
>another procedure?
All current refractive surgery techniques and technologies have the
ability to provide excellent and poor outcomes. Some are more
appropriately suited for an individual's needs than others. There is
no one system, protocol, standard, etc. that fits all people and all
circumstances. You appear to believe that there is only one correct
way to perform refractive surgery, and many, many refractive surgeons
have proven this to be inaccurate assumption. Get 10 refractive
surgeons together and you will have 10 different sets of "standards".
Not very different, but different enough that one is not directly
comparable to another.
> If you don't know, then why don't you ask your
>Doctors and post an answer?
At this point I believe we are still attempting to establish exactly
what you are attempting to talk about.
>How do they pick one laser or one procedure
>over another?
Training and experience.
>
>Thirdly, you have written that you don't monitor what your doctors say
>to patients. If they are NOT using the superior technology, Do you
>think they tell their patients that there is a superior technology
>available? If you don't know, then why don't you ask them?
>Are you just being deliberately vague? Do CRSQA Doctors answer their
>patients questions this way? Rather than providing an answer, they
>answer different questions? When did you have surgery? How's your
>vision?
We evaluate the patient's outcomes, now how a doctor achieves that
outcome. I have facetiously said that if a doctor can consistently
and predictably get a good outcome with a 24-volt battery and a butter
knife, it really does not make any difference. What is important, at
least to the patients, is the outcome. All the technical information
you seem to be attempting to assimilate is second to the patient's
outcome.
lasik advocate with flap melt
normal vision. If you do equate the 2 and you only evaluate patient
satisfaction (subjective satisfaction as you worded it) specifically
with respect to visual acuity and disregard all other factors, then
the satisfaction rate would be much lower. Iatrogenically induced
higher order aberrations are deemed to be normal by what standard?
Central Visual acuity alone without regard to non-central vision?
Since LASIK doesn't guarantee acuity either than as long as the
actuity is correctable with glasses or contacts, then they would count
as "satisfied" even if the vision quality is way worse than before.
Now I understand how it works. CRSQA "quality" only refers to the
quantity of vision, not the quality of vision at all.
Are you saying that ALL LASIK surgeries have resulted in vision
quality equal to the vision quality they had before LASIK? Is normal
vision set by some standard? If so, what is it? You don't equate
visual acuity with visual quality do you?
That makes sense now. Do you explain that on your website somewhere?
Obviously we disagree.
Glenn Hagele - Council for Refractive Surgery Quality Assurance <glenn.hage...@USAeyes.org> wrote in message news:<joadmvg2kd3bdtdmc...@4ax.com>...
lasik advocate with flap melt
the cornea prolate still makes it more oblate than it was before when
it was a normal, healthy cornea (i.e., still flattens the cornea, but
not as much as the other types of LASIK)?
Glenn Hagele - Council for Refractive Surgery Quality Assurance <glenn.hage...@USAeyes.org> wrote in message news:<l0bdmv0uk7rr393r8...@4ax.com>...
lasik advocate with flap melt
order aberrations be eliminated completely with a flattened cornea
that doesn't have the natural prolate shape?
Glenn Hagele - Council for Refractive Surgery Quality Assurance <glenn.hage...@USAeyes.org> wrote in message news:<l0bdmv0uk7rr393r8...@4ax.com>...
Glenn Hagele - Council for Refractive Surgery Quality Assurance
>Are you saying that even the laser technology that supposedly leaves
>the cornea prolate still makes it more oblate than it was before when
>it was a normal, healthy cornea (i.e., still flattens the cornea, but
>not as much as the other types of LASIK)?
Yes, of course.
Glenn Hagele - Council for Refractive Surgery Quality Assurance
>I didn't think this was possible. How can the higher order and lower
>order aberrations be eliminated completely with a flattened cornea
>that doesn't have the natural prolate shape?
You are looking at only one very, very small (although important)
aspect of ocular refraction...and you have not even begun to consider
the functioning of the retina, nervous system, and brain. A more
prolate shape does change the way light refracts, however that does
not necessarily lower vision quality. All the other factors must also
be considered, evaluated, and balanced. If in one place you zig, the
other place you zag, it all comes out in the end.
Of course, this would be only the factors that doctors currently
understand. A scant four years ago there were probably five
opthalmologists in the world who understood the concept of wavefront
as applied to human vision. The understanding and the subsequent
improvements are as infinate as the complexity of human vision.
I've been involved in healthcare in one area or another since 1982.
I've worked with ophthalmology on and off since 1985. I founded and
have operated CRSQA full time for the last five years. For all the
research and understanding I have accummulated over these years, I can
sit down with a knowledgeable surgeon and still be amazed by what I
didn't know.
It is an endeavor of disappointment for you to attempt to gain a
detailed understanding of all the nuances of refractive surgery in the
short time you have had an interest. While your interest is keen and
your desire to understand is admirable, you are getting into areas
where there may only be a few dozen people who could even understand
the questions, let alone the answers.
If you want to know the most there is to know about prolate cornea,
you need to do some searches for Jack Holladay, MD's publications on
the issue. What you will probably find (and believe me, this is no
insult) is that you will be able to grasp some of the concepts, but
not necessarily understand exactly how they relate to other areas of
the vision process. In other words, even if you knew everything that
Jack Holladay knows about prolate v. oblate, you will still be at a
loss because you probably don't know all that Dr. Holladay knows about
all the other equally important and interdependent issues. And even
if you knew everything that Jack Holladay knows about everything, you
still would be without the collective knowledge of all the other great
minds in ocular science.
You can easily research yourself around in circles trying to
understand this all. I've learned to be satisfied to know what I
don't know, and assume it is much more than that! 8^)
Dr. Leukoma
actually have large scotopic pupils. Typically, they do have problems
driving at night. Perhaps we should be looking at doing wavefront on them.
DrG
kpat...@hotmail.com (lasik advocate with flap melt) wrote in
news:b0866067.03091...@posting.google.com: