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Home > Archive > Lasik Eyes Surgery > August 2005 > The Importance of Pupil Measurement
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The Importance of Pupil Measurement
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| Andrea 2005-08-13, 5:55 pm |
| The Importance of Pupil Measurement
By Jack Holladay, MD, MSEE, FACS
http://www.lasikfyi.com/articles10.html
The following abstract was created from the article entitled Inaccurate
Pupillometry Very Costly. The author would like to disclose his financial
interest in the subject: he is the developer of the Holladay Pupil Gauge
from ASICO.
As you may or may not know, people with very large pupils are generally bad
candidates for LASIK and other refractive procedures. As a result, accurate
measurement of a patient's pupils (pupillometry) as a part of the evaluation
for refractive surgery is essential. With reports of halos and glare
following refractive surgery on many of the prime time news shows,
pupillometry has become one of the preoperative tests expected by the
patient. It is very clear from the published and anecdotal reports of
nighttime glare and halos that large pupils are the predominant factor
resulting in these problems.
Avoiding halos and glare:
To understand why nighttime glare and halos occur, it is first important to
understand two central factors: the effective optical zone and scotopic
pupil size. In LASIK, the effective optical zone refers to the portion of
the cornea that the refractive surgeon removes or ablates with the laser in
order to reshape the cornea. Try and imagine the area of the eye covered by
a contact lens. The effective optical zone is very similar.
Scotopic pupil size is the size a patient's pupils dilate to in a dark room.
Postoperative halos are caused by disparity between scotopic pupil size and
the effective optical zone.
Halos are literally a ring of glare seen through the outer portion of the
pupil at night by some patients. This occurs when the diameter of the
central area of the cornea ablated by the surgeon (the effective optical
zone) is not quite as large as the patient's dilated eye at night (the
scotopic pupil size). Ideally, the two should be the same size, and the
effective optical zone should be perfectly centered with the pupil.
Requiring the effective optical zone size to be equal to the scotopic pupil
is the strictest possible criterion a refractive surgeon can follow, but it
is the safest approach. I have treated patients in years past without
following this criterion and most of them were very happy with the results.
However, our understanding of postoperative night vision problems and the
standard of care have increased, and I would be much less likely to treat
these patients the same way today.
In my opinion, today's surgeons should also use a blend zone (literally a
'blended' zone of ablation between the effective optical zone and the outer
edge of the cornea) of 1 or 2 mm to avoid a sharp transition from the
treated to untreated area that can cause unwanted images in the peripheral
vision. This requires the use of a laser capable of creating a blend zone.
Pupillometers
There are three basic types of commercial pupillometers, the instrument used
by refractive surgeons to measure scotopic pupil size. They are: 1)
objective infrared video camera with pupil detecting system (Procyon), 2)
infrared tubes with a reticule or display (Colvard & Pupilscan II), and 3)
gauges (Holladay, Rosenbaum card, etc.).
If you are interested in how each of these instruments works, your
refractive surgeon should be able to explain it to you. However, no matter
what instrument is chosen, the information it reveals should be documented
in the patient's chart and the measurement should be repeated if there is
any question on the part of the technician as to the exact pupil size.
What is considered 'normal' pupil size varies with age and gender. The pupil
gets smaller with age, and men usually have smaller pupils than women of the
same age. Studies show that 67% of refractive surgery patients' pupils are 5
to 7 millimeters in diameter. Since most lasers are capable of ablating out
to 7 millimeters, this means that a majority of refractive surgery patients
should have no problem.
As I stated at the outset, an accurate scotopic pupil measurement as a part
of the preoperative evaluation is just as important as accurately measuring
refraction and thickness of the cornea. This measurement, along with
determining the effective optical zone size, is the best way to avoid
disabling nighttime glare and halos.
Jack Holladay, MD, MSEE, FACS, is Clinical Professor of Ophthalmology at
Baylor college of Medicine. He has devoted his Houston practice, Holladay
Lasik Institute, exclusively to Excimer Laser Vision Correction. Dr.
Holladay is also the developer of the Holladay Pupil Gauge from ASICO.
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Glenn - USAEyes.org wrote:
> Another less technical article on pupil size is at
> http://www.usaeyes.org/faq/subjects..._pupil_size.htm
>
> BTW, the author of the previously cited article is a CRSQA Certified
> Refractive Surgeon and is a member of our governing board.
>
> Glenn Hagele
> Executive Director
> USAEyes.org
>
> "Consider and Choose With Confidence"
>
> Email to glenn dot hagele at usaeyes dot org
>
> http://www.USAEyes.org
> http://www.ComplicatedEyes.org
>
> I am not a doctor.
How can anyone "Consider and Choose With Confidence" when Dr. Holladay
thinks that large pupil patients are bad LASIK candidates, and Dr.
Maloney thinks it's okay that pupils are never measured prior to
surgery? How can a patient be confident in CRSQA surgeons who cannot
even agree on what makes a bad candidate for surgery?
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| crvc@wyoming.com 2005-08-15, 11:54 am |
| I had bilateral LASIK in 1997. Although I'm 20:20 my night vision is
very bad. Recently I was examined by two surgeons. Neither will commit
to the idea of pupil/ablation zone mismatch as a cause for the night
vision problems. Researching the subject on Medline I find abstracts
either supporting the idea or not supporting the idea. My vision is
better if I use dilute pilocarpine eyedrops. This suggests to me that
this mismatch idea is the reason. Maybe someday there will be a
medical consensus on the role of small ablation zones causing night
vision problems. Until that time, I'm stuck in this glare-y,
starburst-y waking nightmare.
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| Glenn - USAEyes.org 2005-08-15, 5:55 pm |
| While Keller may have focused on the pupil size issue, there are many,
many other issues on which knowledgeable and respected doctors do not
agree. If you look at the surgical protocol of 10 different doctors
you will find 10 different protocols. This is true throughout
medicine.
The reason one can be confident in the choice of a surgeon who is
certified by our organization is because we have focused on what is
really important: outcomes. Every doctor certified by our organization
has been evaluated and achieves outcomes that meet our requirements.
They may reach those outcomes by different paths, but the bottom line
is the outcome.
Glenn Hagele
Executive Director
USAEyes.org
"Consider and Choose With Confidence"
Email to glenn dot hagele at usaeyes dot org
http://www.USAEyes.org
http://www.ComplicatedEyes.org
I am not a doctor.
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| Glenn - USAEyes.org 2005-08-15, 5:55 pm |
| The predictability of night vision problems and the treatment of night
vision problems are to totally different issues. Do not confuse
predictability with treatment.
The studies of Dr. Schallhorn and many others have shown that pupil
size alone is an unreliable predictor of night vision problems. Some
people with large pupils do not have night vision problems after
surgery.
If night vision problems are caused by aberrations at the outer edges
of the cornea, then blocking the light passing through the aberrations
from entering the eye and being "seen" by reducing the pupil size is
an appropriate treatment.
Glenn Hagele
Executive Director
USAEyes.org
"Consider and Choose With Confidence"
Email to glenn dot hagele at usaeyes dot org
http://www.USAEyes.org
http://www.ComplicatedEyes.org
I am not a doctor.
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| EyesRBAD 2005-08-17, 10:57 pm |
| A surgeon at a major medical center where other surgeon's LASIK screw-ups
are supposedly fixed claims that 10% of patients have visual symptoms that
are
not recorded by a Snellen chart. Snellen charts are used to measure outcome.
They are not a good measure of outcome and this doctor confirmed this.
40% loss of corneal nerves at 3 years is also not a good outcome. Permanent
corneal pathology is not a good outcome. Universal loss of contrast
sensitivity...
not a good outcome. 100% of LASIK patients have these problems.
A good LASIK outcome is an oxymoron.
"Glenn - USAEyes.org" <glenn.hageleSTOPSPAM@USAEyes.org> wrote in message
news:c4j1g15dovfg5cs95j048j2ia6k2c52eau@4ax.com...
> While Keller may have focused on the pupil size issue, there are many,
> many other issues on which knowledgeable and respected doctors do not
> agree. If you look at the surgical protocol of 10 different doctors
> you will find 10 different protocols. This is true throughout
> medicine.
>
> The reason one can be confident in the choice of a surgeon who is
> certified by our organization is because we have focused on what is
> really important: outcomes. Every doctor certified by our organization
> has been evaluated and achieves outcomes that meet our requirements.
> They may reach those outcomes by different paths, but the bottom line
> is the outcome.
>
> Glenn Hagele
> Executive Director
> USAEyes.org
>
> "Consider and Choose With Confidence"
>
> Email to glenn dot hagele at usaeyes dot org
>
> http://www.USAEyes.org
> http://www.ComplicatedEyes.org
>
> I am not a doctor.
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| Glenn - USAEyes.org 2005-08-17, 10:57 pm |
| Yet another unidentified source of unsubstantiated information from
someone who has provided ample evidence of a anti-LASIK bias and an
inability to accept proven facts.
Glenn Hagele
Executive Director
USAEyes.org
"Consider and Choose With Confidence"
Email to glenn dot hagele at usaeyes dot org
http://www.USAEyes.org
http://www.ComplicatedEyes.org
I am not a doctor.
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| serebel 2005-08-17, 10:57 pm |
| Why should the loon squad deal in facts when they can make up their own
as they go along? I remember a few years ago where they were crying
"cancer" after lasik.
SErebel
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Glenn - USAEyes.org wrote:
>
> The studies of Dr. Schallhorn and many others have shown that pupil
> size alone is an unreliable predictor of night vision problems.
Correct. It's large pupil size AND refractive surgery that cause the
problems.
> Some people with large pupils do not have night vision problems after
> surgery.
Correct. I didn't have any night vision problems after any surgery,
until I had refractive surgery.
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| Glenn - USAEyes.org 2005-08-19, 11:52 am |
| Yet again, rather than participate in an intelligent discussion about
a real limitation of refractive surgery that is being studied and
defined, Keller just blames everything on refractive surgery.
Glenn Hagele
Executive Director
USAEyes.org
"Consider and Choose With Confidence"
Email to glenn dot hagele at usaeyes dot org
http://www.USAEyes.org
http://www.ComplicatedEyes.org
I am not a doctor.
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| Richard 2005-08-19, 5:59 pm |
| "Sandy" <sandy@savvysneaks.com> wrote in news:1124427213.019493.4720
@g47g2000cwa.googlegroups.com:
>
> Glenn - USAEyes.org wrote:
>
> Correct. It's large pupil size AND refractive surgery that cause the
> problems.
>
>
> Correct. I didn't have any night vision problems after any surgery,
> until I had refractive surgery.
>
Don't be a complete idiot here, you know as well as anyone else here what
his statement meant.
I have large pupils, and I had LASIK, and I do not suffer from night
vision problems. Other people who do not have large pupils, and have had
LASIK, or other refractive surgery, do suffer from night vision problems.
There is more likelihood of night vision problems post refractive surgery
if the patient does have large pupils, however, there is no way to say
with certainty prior to surgery whether or not the patient will have
night vision problems based solely on their pupil size.
--
Richard
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| serebel 2005-08-19, 10:55 pm |
|
Glenn - USAEyes.org wrote:
> Yet again, rather than participate in an intelligent discussion about
> a real limitation of refractive surgery that is being studied and
> defined, Keller just blames everything on refractive surgery.
>
Keller has just been ranting lately. I guess there's nothing new on
Hanson's site she can purloin and post here. She's a sorry one who no
one can seriously, even the other loons.
SErebel
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| Sandy 2005-08-20, 10:54 pm |
|
>
> The reason one can be confident in the choice of a surgeon who is
> certified by our organization is because we have focused on what is
> really important: outcomes. Every doctor certified by our organization
> has been evaluated and achieves outcomes that meet our requirements.
> They may reach those outcomes by different paths, but the bottom line
> is the outcome.
>
> Glenn Hagele
> Executive Director
> USAEyes.org
Judy Jade Chang and Kathy Griffin both had lasik done by a CRSQA
surgeon.
Neither of them had good outcomes.
What does CRSQA do when they refer a patient to a certified surgeon and
a bad outcome is the result? Do they refer to another CRSQA surgeon
for repair?
What is the likelihood of getting an honest 2nd opinion from another
CRSQA surgeon?
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| serebel 2005-08-20, 10:54 pm |
| Here goes Sandy holding up the whacko Cathy Griffin again. Griffin had
too many surgeries just like Keller in search of total perfection. They
both screwed themselves up.
SErebel
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| Glenn - USAEyes.org 2005-08-21, 8:54 am |
| I do not know if Ms. Griffin selected her first surgeon because he was
CRSQA certified, or if she selected her second surgeon because he was
CRSQA certified, but both of her doctors are certified by our
organization.
Certification, however, does not mean perfection. There is no such
thing as a perfect surgeon anymore than there is such a thing as a
perfect surgery. Even the very best surgeons have undesired outcomes,
but those who have been evaluated and certified by our organization
have outcomes equal to or better than the national norms.
Of course, the quality of the doctor has absolutely nothing to do with
anything when the patient is noncompliant. Even Griffin has
acknowledged in interviews that she delayed having the flap lift to
remove her epithelial ingrowth. Unfortunately she delayed until some
serious damage occurred.
If there is any lesson to learn from Ms. Griffin's circumstances, it
is that regardless if your surgeon is certified by our organization or
not, if the doctor says come in because you need a problem fixed, do
not delay.
Glenn Hagele
Executive Director
USAEyes.org
"Consider and Choose With Confidence"
Email to glenn dot hagele at usaeyes dot org
http://www.USAEyes.org
http://www.ComplicatedEyes.org
I am not a doctor.
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| Ragnar 2005-08-22, 10:55 pm |
| Give it a rest lady. Everyone here who has followed this group at
all knows you are a complete liar.
The problems you had were almost entirely the result of your own bad
decision making.
You tried to get refractive surgery done for years, and every doctor
you asked said you were a bad candidate for it. You eventually found
some quack that was willing to do it, and although your initial
results were good, you demanded an ill advised enhancement which was
allso done too soon after your initial procedure.. and you also
overdosed on the steroid drops causing your sagging eyelids. The
fact that you got any money for your own stupidity is amazing. You
should have returned that money. The fact that you continue to whine
about this is incredible.
Do they not have mental institutions in California?
I know Ron Link reads every message in this newsgroup. I wonder if he
ever asked hiimself it it was a bad idea in using you as his front to
propagate misinformation. In the long run, I think that association
did more to bring about the demise of S.E. than anything.
Oh, and by the way, your heroine Kathy Griffin's mental illness is
costing her bigtime. Her career is in freefall. She can't even get
on talk shows anymore. She thinks it is because her act is nothing
but attacks upon celebrities. The real reason is that she just isn't
funny. Jay Leno did a fantastic job of cutting her down to size
permanently.
On 18 Aug 2005 21:53:33 -0700, "Sandy" <sandy@savvysneaks.com> wrote:
>
>Glenn - USAEyes.org wrote:
>
>Correct. It's large pupil size AND refractive surgery that cause the
>problems.
>
>
>
>Correct. I didn't have any night vision problems after any surgery,
>until I had refractive surgery.
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| Ragnar 2005-08-22, 10:55 pm |
| you would have a better chance at having an intelligent discussion
with Pauly Shore.
On Fri, 19 Aug 2005 16:34:07 GMT, Glenn - USAEyes.org
<glenn.hageleSTOPSPAM@USAEyes.org> wrote:
>Yet again, rather than participate in an intelligent discussion about
>a real limitation of refractive surgery that is being studied and
>defined, Keller just blames everything on refractive surgery.
>
>Glenn Hagele
>Executive Director
>USAEyes.org
>
>"Consider and Choose With Confidence"
>
>Email to glenn dot hagele at usaeyes dot org
>
>http://www.USAEyes.org
>http://www.ComplicatedEyes.org
>
>I am not a doctor.
| |
| Ragnar 2005-08-22, 10:55 pm |
| Keller, you really are disgusting.
I am not familiar with your garbage about Judy Chang and am not about
to waste my time looking it up.
As for Kathy Griffin, her initial LASIK procedure was a complete
success and she loved it. Then she decided to go for monovision - bad
idea.. then she decided to try and screw the surgeon out of money
rather than get a simple problem fixed. By doing that, her simple
problem became a significant problem.
On 20 Aug 2005 17:25:32 -0700, "Sandy" <sandy@savvysneaks.com> wrote:
>
>
>Judy Jade Chang and Kathy Griffin both had lasik done by a CRSQA
>surgeon.
>
>Neither of them had good outcomes.
>
>What does CRSQA do when they refer a patient to a certified surgeon and
>a bad outcome is the result? Do they refer to another CRSQA surgeon
>for repair?
>
>What is the likelihood of getting an honest 2nd opinion from another
>CRSQA surgeon?
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