|
Home > Archive > Lasik Eyes Surgery > July 2006 > Wavefront lasik and PRK still increases your high order aberrations and distortions!
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
| Author |
Wavefront lasik and PRK still increases your high order aberrations and distortions!
|
|
|
| Very good read and information people did not previously know! Still
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=AE 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'h=C9ineach=E1in
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.
| |
| Rev Jessie James 2006-07-24, 9:26 pm |
| 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!
"Ace" <acemanvx@yahoo.com> wrote in message
news:1153654329.389155.126100@m79g2000cwm.googlegroups.com...
Very good read and information people did not previously know! Still
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 2006-07-24, 9:26 pm |
|
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.
| |
|
|
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 2006-07-25, 8:26 am |
| You don't even know what an aberration is.
On 24 Jul 2006 20:48:25 -0700, "Ace" <acemanvx@yahoo.com> wrote:
>
>Rev Jessie James wrote:
>
>
>
>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
| |
| Rev Jessie James 2006-07-25, 9:25 pm |
| "Ace" <acemanvx@yahoo.com> wrote in message
news:1153799305.553118.75480@m79g2000cwm.googlegroups.com...
> 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 2006-07-26, 2:25 am |
| Frankly.. the risks are so low and they are largely dependent on the
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.
On Wed, 26 Jul 2006 00:27:44 GMT, "Rev Jessie James"
<Jessie@yahoo.com> wrote:
>"Ace" <acemanvx@yahoo.com> wrote in message
>news:1153799305.553118.75480@m79g2000cwm.googlegroups.com...
>
>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..
>
|
| |
|
|