Vision - LASIK eye surgery, starburst

Author

LASIK eye surgery, starburst

Pauli Soininen

2005-04-21, 8:54 am

I have already asked a bit similar type of question before, but since I was
forwarded back here from elsewhere..

As many of you know, in an eye that has been treated with LASIK surgery,
there is a center area (about 6mm) that has perfect refractive correction.
Then there is a transition zone (about 2mm) which has a sliding correction
from perfect to the old (say -5 diopters). Now, if there's a bright light
(and the pupil is 8mm), what will be seen is a light with a starburst/halo
around it.

According to my tests and the picture I see (I have been lasered with
LASIK), I believe the starburst effect I see is completely caused by the
transition zone (I see also other halo layers, but they're not that bad and
we can dismiss them for now). When my pupil dialates, I can clearly see that
the starburst is enlarging from very small (5mm pupil) to quite big (7.7mm
pupil).

The starburst is identical on each lamp (I see many identical starbursts if
there are many lamps). I believe the starburst arm that points directly to
left is caused by the transition zone "slice" in my eye that points directly
to left. If I look at light from a laser pointer I can very accurately see
what's going on, the distortion is very accurate and moving head changes the
distortion.

What I still don't understand is how come I see starburst arms and not an
even halo. Does somebody have an answer for this or even speculation? I have
created a bunch of pictures that I can show and I can answer all your
questions if I forgot to give you some vital information.

Here is a rough approximation of how street lamps look to me (when they are
not close or big enough to change to halos, where individual arms are
duplicated to an even field) ->
http://www.glowfoto.com/viewimage.p...t=jpg&rand=7823

Let's say we have two video projectors with the same image pointing at the
same position on a wall and the other projector would have really bad focus
(somewhat similar to what the LASIK transition zone could be thought to
create). Then we would have just a good image and an evenly spreaded (bad
focus) image superimposed. What is the essential difference in a LASIK
treated eye that creates the starbursts?

PS. If there are any java (or similar) based simulations about eye and how
the image is forming depending on some variables, I would be really
interested to see them (I've seen only basic demonstrations with simple
two-ray representation).

Pauli Soininen

2005-04-21, 5:52 pm

> http://www.revoptom.com/archive/DEPTS/ro0200rs.htm

Thank you. After this I have again found new, essential information.

Let me comment on this article. It is reasonably recently written, though 5
years is "too much" already, I hope there are more recent articles about the
same issues with new, more accurate information. The first four visual
problems mentioned are blur, fog, flare (as a diffractive effect) and soft
focus. I'll make my own interpreatition.

a) blur

Simple spherical refractive error (too much + or -). No deviations.

b) fog (from scatter)

Caused by misaligned lamellar fibers in stroma (a result of microkeratome).
This makes sense. My own fog effect is not so bad or terribly visible, I
could live with it even if it wouldn't heal (and I believe it may well
heal).

c) flare (from diffraction)

There is mistake in the article. It should say "temporarily by contracting"
instead of "temporarily by enlarging".

There is talk about surgeries without a transition zone and so on
(outdated). There is no mention how the starburst arms are formed, that
information is missing. It does suggest though, that non-smoothness will
produce diffractive effects.

d) soft focus

In other words, a case where there is the good focus picture plus bad focus
picture superimposed. Which is probably what is the case on almost all LASIK
patients in some degree. It could be argued how much prolate/oblate will
affect and so on, but my logic would say, that if there is a transition zone
(or a zone with no correction) and the pupil size is somewhere near the
transition zone edge, a picture with bad focus will be present.

At the end, microstriae is mentioned. That makes sense as well. All in all,
I found misaligned lamellar fibers and microstriae particularly interesting.

About your speculation of the natural irregularities of the edge of
the pupil causing the starburst effect: I suspect that is not the case. If I
cover my eye with a card or look through "finger binoculars", I can simply
and clearly reduce the radius of the starburst where I cover the pupil. The
formation of the starburst doesn't change at all, only the radius. And when
the pupil is covered from the edges, I would believe rays of light are not
touching the edges of pupil. But the starburst formation stays intact. That
would indicate the starburst is created in cornea.

Dr. Leukoma

2005-04-22, 8:52 am

Pauli Soininen wrote:
>
> Thank you. After this I have again found new, essential information.
>
> Let me comment on this article. It is reasonably recently written,
though 5
> years is "too much" already, I hope there are more recent articles
about the
> same issues with new, more accurate information. The first four
visual
> problems mentioned are blur, fog, flare (as a diffractive effect) and
soft
> focus. I'll make my own interpreatition.
>
> a) blur
>
> Simple spherical refractive error (too much + or -). No deviations.
>
> b) fog (from scatter)
>
> Caused by misaligned lamellar fibers in stroma (a result of
microkeratome).
> This makes sense. My own fog effect is not so bad or terribly
visible, I
> could live with it even if it wouldn't heal (and I believe it may
well
> heal).
>
> c) flare (from diffraction)
>
> There is mistake in the article. It should say "temporarily by
contracting"
> instead of "temporarily by enlarging".
>
> There is talk about surgeries without a transition zone and so on
> (outdated). There is no mention how the starburst arms are formed,
that
> information is missing. It does suggest though, that non-smoothness
will
> produce diffractive effects.
>
> d) soft focus
>
> In other words, a case where there is the good focus picture plus bad
focus
> picture superimposed. Which is probably what is the case on almost
all LASIK
> patients in some degree. It could be argued how much prolate/oblate
will
> affect and so on, but my logic would say, that if there is a
transition zone
> (or a zone with no correction) and the pupil size is somewhere near
the
> transition zone edge, a picture with bad focus will be present.
>
> At the end, microstriae is mentioned. That makes sense as well. All
in all,
> I found misaligned lamellar fibers and microstriae particularly
interesting.
>
> About your speculation of the natural irregularities of the edge of
> the pupil causing the starburst effect: I suspect that is not the
case. If I
> cover my eye with a card or look through "finger binoculars", I can
simply
> and clearly reduce the radius of the starburst where I cover the
pupil. The
> formation of the starburst doesn't change at all, only the radius.
And when
> the pupil is covered from the edges, I would believe rays of light
are not
> touching the edges of pupil. But the starburst formation stays
intact. That
> would indicate the starburst is created in cornea.

If you really want an optical physicist's explanation of starbursting,
then I suggest you write to Ray Applegate c/o of the university of
Houston college of Optometry. The only reference sources I can find
refer to edge diffraction as well as artifacts in the pathway of the
light, including the crystalline lens. After the light passes through
the cornea, it has to pass through the lens. One thing is absolutely
clear to me, and that is the starbursting is an artifact of the LASIK
surgery. Another certainty is that a properly designed contact lens
will make it go away.

DrG

Andrew Chew

2005-04-22, 11:49 am

"Dr. Leukoma" <drg@leukoma.com> wrote in message
news:1114171221.627056.93490@z14g2000cwz.googlegroups.com...

> If you really want an optical physicist's explanation of starbursting,
> then I suggest you write to Ray Applegate c/o of the university of
> Houston college of Optometry. The only reference sources I can find
> refer to edge diffraction as well as artifacts in the pathway of the
> light, including the crystalline lens. After the light passes through
> the cornea, it has to pass through the lens. One thing is absolutely
> clear to me, and that is the starbursting is an artifact of the LASIK
> surgery. Another certainty is that a properly designed contact lens
> will make it go away.

Probably not relevant but I wear Focus N & Ds and only get starbursts if I
squint.

Pauli Soininen

2005-04-23, 8:53 am

> Probably not relevant but I wear Focus N & Ds and only get starbursts
> if I squint.

Squinting and starbursts. What causes starburst in that situation?

I was thinking it would be a diffractive effect caused by the eyelashes, but
I was not able to proove my theory with a laserpointer light and a
toothbrush. I just couldn't get long starburst arms as they occur when I
simply squint. One reason may be that the brushes in the toothbrush were too
thick (I did separate them a bit).

Anyone have ideas?

Pauli Soininen

2005-04-23, 8:53 am

> I suggest you write to Ray Applegate c/o of the university of
> Houston college of Optometry.

Ok, I will. Thanks!

But what about this: Which is more powerful: aperture size effect itself and
transition zone unmasking in terms of the radius of starburst? Apparently
aperture size itself is a powerful factor to change the defocus radius, like
for example according to this:
http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=55

How is it possible that a person with large pupil and transition zone will
see no starburst (or halo)?

Pauli Soininen

2005-04-23, 8:53 am

> I was not able to proove my theory with a laserpointer
> light and a toothbrush.

In my experiment I held the brush as near as my eye as I could, "simulating"
the eyelashes, but couldn't get long starburst arms at all.

Dr. Leukoma

2005-04-23, 8:53 am

My guess is that it is something other than edge diffraction, i.e.
possibly some type of prism effect from the tear film as a meniscus is
created along the edge of the eyelid. So, instead of diffraction, it
may be refraction, with some modification or contribution by
diffraction, small irregularities in the pupil, lens, etc....but,
mainly refraction.

DrG

Pauli Soininen

2005-04-24, 8:53 am

Xref: newsfeed-west.nntpserver.com sci.med.vision:78720

> http://www.revoptom.com/archive/DEPTS/ro0200rs.htm

Thank you. After this I have again found new, essential information.

Let me comment on this article. It is reasonably recently written, though 5
years is "too much" already, I hope there are more recent articles about the
same issues with new, more accurate information. The first four visual
problems mentioned are blur, fog, flare (as a diffractive effect) and soft
focus. I'll make my own interpreatition.

a) blur

Simple spherical refractive error (too much + or -). No deviations.

b) fog (from scatter)

Caused by misaligned lamellar fibers in stroma (a result of microkeratome).
This makes sense. My own fog effect is not so bad or terribly visible, I
could live with it even if it wouldn't heal (and I believe it may well
heal).

c) flare (from diffraction)

There is mistake in the article. It should say "temporarily by contracting"
instead of "temporarily by enlarging".

There is talk about surgeries without a transition zone and so on
(outdated). There is no mention how the starburst arms are formed, that
information is missing. It does suggest though, that non-smoothness will
produce diffractive effects.

d) soft focus

In other words, a case where there is the good focus picture plus bad focus
picture superimposed. Which is probably what is the case on almost all LASIK
patients in some degree. It could be argued how much prolate/oblate will
affect and so on, but my logic would say, that if there is a transition zone
(or a zone with no correction) and the pupil size is somewhere near the
transition zone edge, a picture with bad focus will be present.

At the end, microstriae is mentioned. That makes sense as well. All in all,
I found misaligned lamellar fibers and microstriae particularly interesting.

About your speculation of the natural irregularities of the edge of
the pupil causing the starburst effect: I suspect that is not the case. If I
cover my eye with a card or look through "finger binoculars", I can simply
and clearly reduce the radius of the starburst where I cover the pupil. The
formation of the starburst doesn't change at all, only the radius. And when
the pupil is covered from the edges, I would believe rays of light are not
touching the edges of pupil. But the starburst formation stays intact. That
would indicate the starburst is created in cornea.

Andrew Chew

2005-04-24, 5:56 pm

Pauli Soininen

2005-04-25, 8:53 am

> possibly some type of prism effect from the tear film as
> a meniscus is created along the edge of the eyelid.

Sounds reasonable. This would be so easy to confirm... If there was a
program for this kind of purpose. I have experimented with a software called
Zemax, which is a optical designer software. I'm not sure if it is able to
render "end-result" images in a "normal" way. It is full of different types
of image analysis, but so far I wasn't that successful.

LarryDoc

2005-05-06, 12:00 pm

In article <1115389308.048631.41850@z14g2000cwz.googlegroups.com>,
"Dr. Leukoma" <drg@leukoma.com> wrote:

> All kidding aside, Larry, there is a serious side to this topic, which
> is the retreatment of higher order aberrations created by LASIK with
> another laser procedure. If it works, great. If it doesn't work, the
> patient can wind up worse off in my experience. Sometimes, far worse.

It is that last sentence that sends chills up my spine.

> On the other hand, a contact lens fix will virtually never makes the
> patient worse than before.

Absolutely, and technology is heading the right direction. Sadly it had
to be market-driven, but none the less the right direction.

And for those LASIK's folks with problems, my posts on the subject,
kidding or not, should not be taken as a lack of concern for your
plight. I can only imagine what it must be like to excitedly go through
a procedure that's supposed to vastly improve the quality of life and
have it go the other way. I certainly hope that a fix is available for
you and that other people can avoid poor outcomes.

LB, O.D.

Scott Seidman

2005-05-06, 12:00 pm

"Dr. Leukoma" <drg@leukoma.com> wrote in news:1115389308.048631.41850
@z14g2000cwz.googlegroups.com:

> On the other hand, a contact lens fix will virtually never makes the
> patient worse than before.
>
> DrG
>
>

But, the patient had surgery in the first place to avoid the contact lens.
I guess each patient needs to assess the degree of risk threshold on their
own.

Scott

William Stacy

2005-05-06, 12:00 pm

I'm not so sure about that. It seems that since the flap never really
"heals", and all lasik eyes are more prone to DLK development than
normal eyes, and the sudden development of late dlk (many years later,
maybe forever, which can be serious) can apparently be stimulated by
even minor epithelial insult, such as might be caused by RGP wear, I'm
beginning to get a bit uneasy about recommending lasik to *anyone*.
Anybody want to comfort my uneasiness?

w.stacy, o.d.

Dr. Leukoma wrote:
> All kidding aside, Larry, there is a serious side to this topic, which
> is the retreatment of higher order aberrations created by LASIK with
> another laser procedure. If it works, great. If it doesn't work, the
> patient can wind up worse off in my experience. Sometimes, far worse.
>
> On the other hand, a contact lens fix will virtually never makes the
> patient worse than before.
>
> DrG
>

Dr. Leukoma

2005-05-06, 5:57 pm

Yes, and that certainly poses a psychological barrier to a number of
patients. On the other side of the coin, many patients also become
rather "gunshy" about future surgeries as a result of a bad experience.

DrG

Dr. Leukoma

2005-05-06, 5:57 pm

I've never seen it happened, and I've fitted quite a few post-LASIK
patients. I've even had a a few put their Macrolens in their eye with
cleaner, thinking that it was wetting solution. I think the DLK scare
is a bit overblown.

DrG

Dr. Leukoma

2005-05-18, 11:27 am

Schallhorn, et. al. suggest that NVD improves by six months. I've not
heard or read anything to suggest that NVD worsens after 3 months.
Also, my impression is that more than 1 or 2 percent of patients have
permanent NVD. But, if you are as good a researcher as I think you
are, you already know this.

Corneal healing is most active at 3 to 4 months following surgery.

DrG

Dr. Leukoma

2005-05-18, 11:27 am