Lasik Eyes Surgery - Check out this vision simulations link

Author

Check out this vision simulations link

Informer

2005-05-18, 11:46 am

All the patients who have responded in writing or verbally about this
simulator say it underestimates the visual trash that they see.

Try it with the worst case scenario and ask yourself if you
could live with that sort of night vision.

http://www.lasik-center.com/simulat...ssimulator.html

Ragnar

2005-05-18, 11:46 am

That's not a bad simulator. It's vastly superior to the ridiculous
simulations put out by Roger Davis.
Altough this simulator is also an exagerration, it's not that far off
the mark. The only major criticism I have of it is that the first
panel shows the vision of a normal 20/20 eye. That panel is not
relevant since there is nothing that is going to make a -10.0 eye with
8mm pupils see like panel #1.
The thing to pay attention to is the dramatic improvement from panel 2
to 3. If that is the WORST case scenario, I'd say that's no so bad.
Keep in mind that this is only a high contrast situation where the
pupils are dilated due to the outside darkness and the eyes are being
hit with headlights and streetlights.
One other criticism. The lighting conditions are deceptive in that it
has a relatively lit sky that is not illuminating the roadway or
objects on the ground at all. This phenomenon only occurs for about
15 minutes a day at dawn and 15 minutes a night at dusk when the sun
is not in the sky but light is being reflected through the atmosphere
over the horizon.

At least this simulator is worth discussing.

On Fri, 13 May 2005 23:23:10 -0400, "Informer"
<Informer@Yahoo_nospam.com> wrote:

>All the patients who have responded in writing or verbally about this
>simulator say it underestimates the visual trash that they see.
>
>Try it with the worst case scenario and ask yourself if you
>could live with that sort of night vision.
>
>http://www.lasik-center.com/simulat...ssimulator.html
>

2005-05-18, 11:46 am

In article <1116040991.4361b7d879fa38e6da79e311754e6c27@teranews>,
"Informer" <Informer@Yahoo_nospam.com> wrote:

> http://www.lasik-center.com/simulat...ssimulator.html

I tried it (-4 to -6) and 5 mm pupils and I would say that the post
LASIK image is exactly how I see. Lights are slightly softer and haloed
after LASIK.

--
~RT
The truth lies somewhere between Ragnar and LASIKtruth
Two sides of the same coin

Pauli Soininen

2005-05-18, 11:46 am

> http://www.lasik-center.com/simulat...ssimulator.html

Well, I would call this simulation almost misleading or at least highly
inaccurate and inadequate. First of all, if in reality the distortion would
be as mild as it is on this simulator, there would not be so many complaints
post-op.

A proper simulator would have much bigger resolution, more images of
different illumination level, much more accurate starburst and halo
simulation (including written information) and so on.

Also the middle image is false too, it has probably just been blurred
(gaussian blurred?), but that's an incorrect method. The lights don't get so
dark in reality as it is here. The correct method is a certain kind of lens
blur. Also I don't understand why there's greater contrast in large pupil
images than in small pupil images. With large pupil the cars should be
brighter, not the other way around. But, you have to remember that retina is
highly adaptive itself, the pupil size actually doesn't have so much effect
on the brightness.

For those who are considering refractive surgery, my advice is not to trust
this simulation at all.

Ragnar

2005-05-18, 11:46 am

I tend to agree with you. That simulation is a bit too simplistic.
Post op complaints in the initial healing phase of lasik are common -
they don't call it a healing phase for nothing.
What I find interesting is that the healing in my case was not a
gradual thing. There would be times of improvement and then
regression and improvement again, however the major changes to my
vision happened in time periods of hours or less. One curious effect
I had for at least 8 months was that the vision in one eye had a
slight blue tint. That effect vanished and hasn't returned.

This simulator at least gives an idea of what to expect. The Roger
Davis simulators are so exagerrated that someone would have to be a
total idiot to even consider them.

Simulating anything isn't an easy thing to do.

On Sat, 14 May 2005 13:00:36 GMT, "Pauli Soininen" <no@spam.com>
wrote:

>
>Well, I would call this simulation almost misleading or at least highly
>inaccurate and inadequate. First of all, if in reality the distortion would
>be as mild as it is on this simulator, there would not be so many complaints
>post-op.
>
>A proper simulator would have much bigger resolution, more images of
>different illumination level, much more accurate starburst and halo
>simulation (including written information) and so on.
>
>Also the middle image is false too, it has probably just been blurred
>(gaussian blurred?), but that's an incorrect method. The lights don't get so
>dark in reality as it is here. The correct method is a certain kind of lens
>blur. Also I don't understand why there's greater contrast in large pupil
>images than in small pupil images. With large pupil the cars should be
>brighter, not the other way around. But, you have to remember that retina is
>highly adaptive itself, the pupil size actually doesn't have so much effect
>on the brightness.
>
>For those who are considering refractive surgery, my advice is not to trust
>this simulation at all.
>

Pauli Soininen

2005-05-18, 11:46 am

> What I find interesting is that the healing in my case was not a
> gradual thing. There would be times of improvement and then
> regression and improvement again, however the major changes
> to my vision happened in time periods of hours or less.

That sounds strange to me. Because of the tear film (or it's absence),
physical pressure etc. the vision can change quickly, but can you give exact
examples what happened to your vision in time period of hours or less?

Growth of epithelium can cause regression or improvement of more permanent
nature, but I would imagine it's close to impossible for that to happen in
matter of hours. Even stroma can grow, according to some research, but that
too should probably take days instead of hours. Changes in inner hydration
level can probably change quite quickly but maybe this happens mainly in the
very first days post-op?

> The Roger Davis simulators are so exagerrated
> that someone would have to be a total idiot to even
> consider them.

Hmm, I'm not sure if they are necessarily that exagerrated. I have some
distortion almost as severe as there is. And I had actually quite good
specifications, very good doctor and top quality equipment.

The simulation I most disagree with those is that loss of contrast
sensitivity image with two boys playing football. I don't see how that could
happen in that particular way. There is written: "Perceptually, this effect
is similar to turning down the Contrast adjustment on your television of
monitor." I totally disagree, I think contrast adjustment on television
works in a totally different way than the so called contrast sensitivity
problem after refractive surgery.

Pauli Soininen

2005-05-18, 11:46 am

> And I had actually quite good specifications, very
> good doctor and top quality equipment.

And I might add also a "perfectly" successful operation and recovery
according to the doctor.

Note though that I'm not trying to scare anyone with this and I'm not
against refractive surgery, I just want there to be a better level of
knowledge.

Informer

2005-05-18, 11:46 am

The tear film is disrupted after LASIK, and drying can be gradual. You may
experience fluctuations in your vision with each blink or at different times
of the day. I still do have varible vision between blinks and at differnt
times of the day over a year after my LASIK. This unpleasant side effect of
LASIK should be clearly spelled out in informed consent matierials.
"Pauli Soininen" <no@spam.com> wrote in message
news:Q1phe.206$sa3.117@read3.inet.fi...
>
> That sounds strange to me. Because of the tear film (or it's absence),
> physical pressure etc. the vision can change quickly, but can you give
> exact examples what happened to your vision in time period of hours or
> less?
>
> Growth of epithelium can cause regression or improvement of more permanent
> nature, but I would imagine it's close to impossible for that to happen in
> matter of hours. Even stroma can grow, according to some research, but
> that too should probably take days instead of hours. Changes in inner
> hydration level can probably change quite quickly but maybe this happens
> mainly in the very first days post-op?
>
>
> Hmm, I'm not sure if they are necessarily that exagerrated. I have some
> distortion almost as severe as there is. And I had actually quite good
> specifications, very good doctor and top quality equipment.
>
> The simulation I most disagree with those is that loss of contrast
> sensitivity image with two boys playing football. I don't see how that
> could happen in that particular way. There is written: "Perceptually, this
> effect is similar to turning down the Contrast adjustment on your
> television of monitor." I totally disagree, I think contrast adjustment on
> television works in a totally different way than the so called contrast
> sensitivity problem after refractive surgery.
>

Informer

2005-05-18, 11:46 am

Unfortunately for many, the aberrations seen in the healing phase are
permanent. Almost every patient has an increase in higher order aberrations
over a year out from treatment - these are the aberrations that cause visual
distortions and when they are seen past the 1 year follow up you can assume
you are stuck with them. ALMOST EVERY LASIK PATIENT GETS PERMANENT
LASIK-INDUCED ABERRATIONS.
"Ragnar" <ragnarsuomi@yahoo.com> wrote in message
news:nq1c81dld9u5mflcna6q40jtu8hs8dj342@4ax.com...
>I tend to agree with you. That simulation is a bit too simplistic.
> Post op complaints in the initial healing phase of lasik are common -
> they don't call it a healing phase for nothing.
> What I find interesting is that the healing in my case was not a
> gradual thing. There would be times of improvement and then
> regression and improvement again, however the major changes to my
> vision happened in time periods of hours or less. One curious effect
> I had for at least 8 months was that the vision in one eye had a
> slight blue tint. That effect vanished and hasn't returned.
>
> This simulator at least gives an idea of what to expect. The Roger
> Davis simulators are so exagerrated that someone would have to be a
> total idiot to even consider them.
>
> Simulating anything isn't an easy thing to do.
>
> On Sat, 14 May 2005 13:00:36 GMT, "Pauli Soininen" <no@spam.com>
> wrote:
>
>

Ragnar

2005-05-18, 11:46 am

That is nonsense.

Also, there are bad aberrations and good/beneficial aberrations. The
shape of the cornea must be made "abnormal" to compensate for the
elongated eye. Since the shape of the entire eye can't be altered,
adjusting the shape of the cornea is the next best thing.

On Sat, 14 May 2005 12:50:13 -0400, "Informer"
<Informer@Yahoo_nospam.com> wrote:

>Unfortunately for many, the aberrations seen in the healing phase are
>permanent. Almost every patient has an increase in higher order aberrations
>over a year out from treatment - these are the aberrations that cause visual
>distortions and when they are seen past the 1 year follow up you can assume
>you are stuck with them. ALMOST EVERY LASIK PATIENT GETS PERMANENT
>LASIK-INDUCED ABERRATIONS.

Pauli Soininen

2005-05-18, 11:46 am

> The shape of the cornea must be made "abnormal" to
> compensate for the elongated eye. Since the shape of
> the entire eye can't be altered, adjusting the shape of
> the cornea is the next best thing.

Do you have some research findings about this? I believe you are talking
about prolate vs. oblate. Every point in the light source is hitting every
point in the cornea. I am doubtful that by changing the cornea it would be
possible to optimize the picture for an elongated retina (steeper curvature
of retina). If the crystalline lens counter-matches the shape or power of
cornea (and the total refraction matches the length to the retina), then the
picture is optimal, I believe. Assuming that the retina is not aberrated
itself (which I would imagine is usually the case).

Ragnar

2005-05-18, 11:46 am

Your trying to bury the obvious in a sea of babble.

Lets bring this back to reality by illustrating the point made. In
this case, lets consider the eye's natural crystalline lens which you
dragged into the discussion.
Lets say there are two patients, one with normal eyes, one with
elongated myopic eyes. Both have "normally" shaped crystalline
lenses. To compensate for the incorrect shape of the elongated myopic
eye, an abnormally shaped IOL could be used to replace the natural
lens which is normal.

Rather than go on about why you don't think people should have lasik,
why don't you tell us what you think people should do to see well when
they have myopic eyes?
Glasses are fine for low myopes with less than 2 diopters of error.
The lenses will be very light and thin and the patient can still
function with their glasses off. At -7.00, glasses are impractical,
heavy, and leave the patient blind when the glasses fog up or are not
on.
Contacts are fine when they don't fall out or slip onto the sclera or
fold up or dry out or trap lipids or dust or hair under them, or
scratch the cornea, or irritate the epithelium, etc. And again, at
-7.00, when those lenses are not in, you are virtually blind.

You have some more solutions?

On Sat, 14 May 2005 18:41:09 GMT, "Pauli Soininen" <no@spam.com>
wrote:

>
>Do you have some research findings about this? I believe you are talking
>about prolate vs. oblate. Every point in the light source is hitting every
>point in the cornea. I am doubtful that by changing the cornea it would be
>possible to optimize the picture for an elongated retina (steeper curvature
>of retina). If the crystalline lens counter-matches the shape or power of
>cornea (and the total refraction matches the length to the retina), then the
>picture is optimal, I believe. Assuming that the retina is not aberrated
>itself (which I would imagine is usually the case).
>

Pauli Soininen

2005-05-18, 11:46 am

> Rather than go on about why you don't think people should
> have lasik, why don't you tell us what you think people should
> do to see well when they have myopic eyes?

I realize now that you are willing to talk about whether people should have
LASIK or not, or actually you want to say that LASIK is a good invention. I
don't find it fruitful to participate in that conversation. But as I
mentioned, I'm not against LASIK (when the patient knows the risks and the
compromises that have to be made).

I thought you might have some good understanding of the prolate/oblate
question and was interested to hear that, and that's why I was trying to ask
for more information about it. Anyway, LASIK is not just about compensating
elongated eye with an ablation pattern calculated to match perfectly the
elongation. The ablation pattern can probably never be optimal and that is
because there isn't enough of stroma to take away. After LASIK the vision
will be good if the eye heals as predicted and if bunch of other, partly
unknown factors fall into place.

Ragnar

2005-05-18, 11:46 am

I suppose someone could argue whether or not the wheel and fire were
good inventions.
Since I see better now without contacts or glasses than I ever did
WITH contacts or glasses, I think it's a pretty good invention.

The oblate/prolate debate isn't very relevant to the U.S. consumers
becase we don't have the MEL system available.

On Sun, 15 May 2005 09:49:27 GMT, "Pauli Soininen" <no@spam.com>
wrote:

>
>I realize now that you are willing to talk about whether people should have
>LASIK or not, or actually you want to say that LASIK is a good invention. I
>don't find it fruitful to participate in that conversation. But as I
>mentioned, I'm not against LASIK (when the patient knows the risks and the
>compromises that have to be made).
>
>I thought you might have some good understanding of the prolate/oblate
>question and was interested to hear that, and that's why I was trying to ask
>for more information about it. Anyway, LASIK is not just about compensating
>elongated eye with an ablation pattern calculated to match perfectly the
>elongation. The ablation pattern can probably never be optimal and that is
>because there isn't enough of stroma to take away. After LASIK the vision
>will be good if the eye heals as predicted and if bunch of other, partly
>unknown factors fall into place.
>

Robert Martellaro

2005-05-18, 11:47 am

On Sat, 14 May 2005 10:44:02 GMT, Ragnar <ragnarsuomi@yahoo.com> wrote:

>That's not a bad simulator. It's vastly superior to the ridiculous
>simulations put out by Roger Davis.
>Altough this simulator is also an exagerration, it's not that far off
>the mark. The only major criticism I have of it is that the first
>panel shows the vision of a normal 20/20 eye. That panel is not
>relevant since there is nothing that is going to make a -10.0 eye with
>8mm pupils see like panel #1.

That's not true. Wearers of rigid Cls would, as well as most soft CL wearers.
Except for reduced image size (about 14%), eyeglasses would also achieve that
quality of vision if the lenses are properly designed and fabricated.

>The thing to pay attention to is the dramatic improvement from panel 2
>to 3.

Actually panel #2 is not relevant to the discussion and is actually inaccurate
for most hyperopes.

> If that is the WORST case scenario,

It is not.

>I'd say that's no so bad. Keep in mind that this is only a high contrast
>situation where the pupils are dilated due to the outside darkness and the eyes
>are being hit with headlights and streetlights.

Right. Night driving, movies, theater, night time sporting events, etc.
I wonder if this simulator takes into account the loss of contrast sensitivity?

>One other criticism. The lighting conditions are deceptive in that it
>has a relatively lit sky that is not illuminating the roadway or
>objects on the ground at all. This phenomenon only occurs for about
>15 minutes a day at dawn and 15 minutes a night at dusk when the sun
>is not in the sky but light is being reflected through the atmosphere
>over the horizon.

Probably true for contrast sensitivity problems, but for starbursting, glare,
and flare I would expect this to be much worse at night/ high contrast
conditions.
>
>At least this simulator is worth discussing.

Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
robopt@execpc.com
~~~~~~~~~~~~~~~~~~
"An expert is a person who has made all the mistakes that can be made in a very narrow field."
- Niels Bohr