Wavefront lasik and PRK still increases your high order aberrations and distortions!
Ace
want lasik/prk after you are done reading the facts below?
Despite what many claim they experience, you cannot have better vision
post PRK than you would have pre-PRK with correction. All types of
refractive surgery induce higher order aberrations. Even customized
wavefront ablations. The aberrations that wavefront guided ablations
induce are just not as severe.
>From the Bausch and Lomb website regarding their Zypotix vision
correction systems which couples their Zywave aberrometer and their
orbscan topographer with their Technolas 217z laser:
Although the ZyWave® Wavefront System measures the refractive error
and wavefront aberrations of the human eyes, including myopia,
hyperopia, astigmatism, coma, spherical aberration, trefoil, and other
higher order aberrations through fifth order, in the clinical study for
this PMA, the average higher order aberration did not decrease after
Zyoptix Personalized Vision Correction.
The aberrations induced by wavefront PRK are simply not as bad as those
induced by traditional PRK. What does this mean?: All refractive
surgeries induce aberrations, which can lead to decreased contrast
sensitivity (among other things such as haloes, double vision,
starbursts), and it is impossible, at least with todays technology, to
have better vision with PRK than what you would be able to get with
contacts. This is especially true with RGPs, which can decrease higher
order aberrations by around 70% (much better than you would get with
PRK, which at best is no net gain in aberrations).
Wavefront-guided PRK causes less increase in overall aberrations than
conventional PRK in myopic patients
Roibeard O'hÉineacháin
in Rome
CUSTOMISED PRK using the Zyoptix (Bausch and Lomb) system appears to
increase higher order aberrations to a lesser degree than conventional
PRK in patients with myopic astigmatism, according to the results of an
Italian study presented at the 7th ESCRS Winter Refractive Surgery
Meeting.
In spite of the improvement caused by the addition of these features,
custom wavefront guidance leads to ablations that often increase
higher-order aberrations, Dr. Holladay says.
http://www.grendahl.com/wavefront/wavefront_system.html
High order aberrations no one wants!
When comparing wavefront to standard LASIK there was an attempt during
an Ophthalmic devices panel meeting to include the word 'reducing' when
referring to higher order aberrations. Aberrations induced by wavefront
are reduced when compared to standard LASIK, but they are CERTAINLY not
reduced when compared to the virgin eye. Wavefront treatments, in fact,
were found to induce aberrations in virgin eyes in clinical trials. A
conscientious doctor on the panel put the skids under the use of the
term 'reducing' when describing wavefront aberrations. Thank you, Dr.
Bullimore.
-----------------------------------------------
Excerpt:
http://www.fda.gov/ohrms/dockets/ac...ipts/3883t1.doc
DR. WEISS: Can you repeat the first one again?
DR. GRIMMETT: Sure. Wavefront-guided LASIK does not reduce the level of
higher-order aberrations of the preoperative eye.
DR. WEISS: Would that not be confusing to someone? Wouldn't that be
confusing?
DR. GRIMMETT: Michael Grimmett.
It may suggest somehow wording in that wasn't it that the higher-order
aberrations were 20 percent higher than the preop eye in the
wavefront-guided versus what, 80 percent was the number?
PARTICIPANT: Seventy-seven percent.
DR. WEISS: In here, is there any place saying that LASIK itself
increases aberrations and that customized corneal ablation increases
them less than conventional treatment?
DR. GRIMMETT: I think that's the idea.
DR. WEISS: So maybe we could put that wavefront-guided ablation ??
DR. GRIMMETT: Conventional LADARVision LASIK increases higher-order
aberrations by that figure 77 percent while wavefront-guided LASIK
increases them by whatever, 20 percent, whatever the number is, or you
can say reduces them to a 20-percent level, if you want to use the word
"reduces."
DR. BULLIMORE: I would avoid the term "reducing."
-------------------------------------------------
So when you say spherical aberration is 'reduced', it's reduced
compared to WHAT, in what population? Is spherical aberration 'reduced'
for large pupil patients as well (likely NOT). Are total higher order
aberrations decreased?
Please keep in mind that in VISX clinical trials, from the data we have
available... 1 in 5 patients did not hit 20/20 at the 12 month mark.
So wavefront can't even do reliably what glasses can do. Let alone the
induced corneal distortions and fried nerves.
I completely agree with Dr. G on this. The overwhelming liklihood is
that refractive surgeons are still out there giving patients corneal
distortions without their informed consent.
I think patients who do their research will find that the strongest,
healthiest and least aberrated corneas they will ever have are their
virgin corneas.
serebel
The above post is total crap. The retard is just regurgitating
"flappie" garbage.
Ace
serebel wrote:
> The above post is total crap. The retard is just regurgitating
> "flappie" garbage.
In defense of lasik and prk, hopefully oneday in the future, they find
a way to actually *remove* aberrations without inducing lots more
aberrations. What they need is a laser a micron in size because thats
how small the aberrations are. Todays flying spot laser is half a
milimeter and only good for refractive errors.
Ragnar
To correct the refractive error in the eye, wavefront intentionally
creates "aberrations" which re-direct the light coming into the eye to
focus upon the retina. The aberrations compensate for the other
errors in the shape of the eye that cannot be modified.
Do you get it now?
Rev Jessie James
I agree that excessive higher order aberrations can lead to loss of
contrast, starbursts, and ghosting. From your posts, it seems like you
conclude that all lasik patients have excessive HOA resulting in poor
vision, which is simply not true.
I assume there is a certain limit to the acceptable HOA resulting from
lasik. I agree that the ideal HOA introduced by lasik would be "0", which
is not achieveable by the current lasik procedure. I would be willing to
bet that the resulting HOA from a "successful" lasik surgery would be many
times below the noticable limit.
So even if my vision is only 99.9% as good as it was prior to lasik, I
sure can't notice it. From my personal experience, I can honestly say I
prefer my post lasik vision to what I was able to see through contacts
and/or glasses. This is hardly a reason to not have lasik!
"Ace" <acem...@yahoo.com> wrote in message
news:1153654329.3...@m79g2000cwm.googlegroups.com...
serebel
Rev Jessie James wrote:
> Ace,
>
> I agree that excessive higher order aberrations can lead to loss of
> contrast, starbursts, and ghosting. From your posts, it seems like you
> conclude that all lasik patients have excessive HOA resulting in poor
> vision, which is simply not true.
>
Ace is too thick to understand logic or reason, you can explain to
him til the cows come home, it won't matter.
Ace
Ragnar wrote:
> You have a very thick skull.. let's try this again..
>
> To correct the refractive error in the eye, wavefront intentionally
> creates "aberrations" which re-direct the light coming into the eye to
> focus upon the retina. The aberrations compensate for the other
> errors in the shape of the eye that cannot be modified.
>
> Do you get it now?
Then explain why all forms of lasik induce aberrations and if you say
aberrations are not a bad thing then *why* are people choosing
wavefront? Also why are all the websites speaking against high order
aberrations as a bad thing if you disagree? You are confusing high
order aberrations with low order aberrations. Low order aberrations are
sphere and cylindar which lasik induces in the opposite direction to
correct your refractive error. High order aberrations are NEVER good.
Its like the aberrations in an old pair of banged up scratched glasses.
Ace
Rev Jessie James wrote:
> Ace,
>
> I agree that excessive higher order aberrations can lead to loss of
> contrast, starbursts, and ghosting. From your posts, it seems like you
> conclude that all lasik patients have excessive HOA resulting in poor
> vision, which is simply not true.
>
> I assume there is a certain limit to the acceptable HOA resulting from
> lasik. I agree that the ideal HOA introduced by lasik would be "0", which
> is not achieveable by the current lasik procedure. I would be willing to
> bet that the resulting HOA from a "successful" lasik surgery would be many
> times below the noticable limit.
>
> So even if my vision is only 99.9% as good as it was prior to lasik, I
> sure can't notice it. From my personal experience, I can honestly say I
> prefer my post lasik vision to what I was able to see through contacts
> and/or glasses. This is hardly a reason to not have lasik!
You do have a point sir. Some or most people dont end up with an overly
large number of aberrations so they notice very little degratation in
vision, ive seen pictures and descriptions and I agree that its
something that can easily be ignored and the impact on vision is very
small. One person ended up with small, transparent halos around lights,
including the three street lights around his house. He said if thats
the worst lasik gave me, it went 99% well and thats good enough to make
me very happy.
You also back the fact all laser surgury induces aberrations, what
someone hopes when going under the laser is not to get *too* many
aberrations induced. Big pupils and picky people arent good candidates.
Those who arent picky are gonna be happy even with some extra
aberrations as long as their vision isnt seriously degraded. I know
this lady in *person* who got lasik back in 2000 and it sounds like she
has lots of aberrations but shes still happy. She sees huge glare and
halos around lights, her vision is only 20/30, her contrast reduced and
who knows what else.
Some people take the risks very seriously, especially if their own
lasik went bad. I am not out on an agenda, I just want to inform people
to think long and hard before deciding on a risky, permanent procedure.
Youd be supprised some people dont have a good reason, others have
unrelistic expectations. I just shake my head when low myopes entering
presbyope trade up glasses, they too regret it in a few years. Most
surgeons dont care but a few will offer monovision or warn you about
presbyopia and tell you to reconsider
Ragnar
Actually.. the LASIK procedre is just about the ONLY way to REMOVE the
most severe and common aberration known as ASTIGMATISM you idiot.
And as for "all the websites speaking against HOA"... what websites
might that be? Lasikfraud, lasikflap, lasiksucks,
lasikmademydickshrink, lasikholocaust ?
You don't have a clue of what you speak of. Go flip some burgers.
Ragnar
Ace
Ragnar wrote:
> do you just make this stuff up?
>
> Actually.. the LASIK procedre is just about the ONLY way to REMOVE the
> most severe and common aberration known as ASTIGMATISM you idiot.
>
> And as for "all the websites speaking against HOA"... what websites
> might that be? Lasikfraud, lasikflap, lasiksucks,
> lasikmademydickshrink, lasikholocaust ?
>
>
> You don't have a clue of what you speak of. Go flip some burgers.
astigmatism is a low order aberration. I was talking about *high* order
aberrations. Of course lasik removes astigmatism, but it makes high
order aberrations worse. high order aberrations are sphere, coma,
trefoil, tetrafoil, pentafoil, secondary astigmatism, etc lots of
polynominals. They are the reason why most humans see only 20/20,
20/25, even 20/30 with glasses. Some humans have less aberrations and
can see very well like 20/15. Do away with every aberration and humans
will see like a hawk in the day and like an owl(almost?) at night!
Ragnar
that really matter. HOAs are trivial by comparison.
A low order aberration is like a mountain.. whereas a high order
aberration is like a molehill.
Rev Jessie James
> to think long and hard before deciding on a risky, permanent procedure.
Ace,
I think statements like this are why people react to you so negatively in
this newsgroup. I agree lasik it is not "risk free" but far less risky
than you claim.
Prior to lasik I researched it about it for almost 2 years before finally
having it done. My decision maker was an elbow in to my glasses, breaking
the frame and needing 6 stitches between my eyelid and my eyebrow. Even
wearing glasses is not entirely "risk free".
I agree any permanent procedure should be research and not done on a whim..
Ragnar
pre-op condition of the patients eyes.. that the only realistic
information a patient can get is from their surgeon. This newsgroup,
any website, nor a consultant is an acceptable source for considering
complications. The trick is to find a good surgeon.
Ace
Ragnar said:
> Here's some more news for you... low order aberrations are the ones
> that really matter. HOAs are trivial by comparison.
>
> A low order aberration is like a mountain.. whereas a high order
> aberration is like a molehill.
This is one of the few times you said something so brilliant! Great
analogy. Low order aberration can blur vision to 20/400, 20/800 or much
worse, like in your case. While high order aberrations "blur" to around
20/20-20/30 but some with bad lasik results can have much more
significent blur and see worse than 20/40 BCVA. Still given the fact
lasik induces more molehills, your vision wont be crisp and perfect,
but "good enough" and much, much better than before without glasses.
Rev Jessie James said:
"I think statements like this are why people react to you so negatively
in
this newsgroup. I agree lasik it is not "risk free" but far less risky
than you claim."
Only lasik surgeons know for sure and even that, some dont because
patients may have too much pride to always report complications,
especially if they are minor. Complications is very broad and both
subjective as well as objective. People argue all the time exactly how
risky lasik is and depending who you listen, youll get totally
different figures. Some things are for certain, poor candidates take an
unacceptable risk, good surgeons will weed those out. Pupil size is one
factor that often goes ignored or downplayed.
"Prior to lasik I researched it about it for almost 2 years before
finally
having it done. My decision maker was an elbow in to my glasses,
breaking
the frame and needing 6 stitches between my eyelid and my eyebrow.
Even
wearing glasses is not entirely "risk free"."
Had you not been wearing glasses, the elbow would have been in to your
eye, causing occular trauma. I had my own glasses protect me more than
once from stuff like flying insects, falling leaves and twigs, fingers
and elbows. Once a door slammed in my face and scratched my glasses
badly instead of brusing my eye! Its a good thing you researched lasik.
If you understood and accepted all the risks, you were well informed
and willing to accept whatever outcome happened, good or bad. To be
honest, those who arent aware or oblivious of the risks are the ones
that end the most unhappy and vocal if their lasik goes bad!
serebel
Ace wrote:
>
>
> Had you not been wearing glasses, the elbow would have been in to your
> eye, causing occular trauma.
You just have to be hit around the eye to have one's glasses broken.
> I had my own glasses protect me more than
> once from stuff like flying insects, falling leaves and twigs, fingers
> and elbows.
Nope, something penetrated your brain.
> Once a door slammed in my face and scratched my glasses
> badly instead of brusing my eye!
Get used to this, for you, it will happen all the time.
lasikrollette
Can't leave you boys alone for a minute now can we.
Stupid jerk assholes.
serebel
lasikrollette wrote:
> I see the two third graders from hell are still here.
> Can't leave you boys alone for a minute now can we.
> Stupid jerk assholes.
Oh yeah? Well, your sister!!!!!! Neener, neener, neener!!!