Lasik and large pupils

Good evening!

With the advent of "CustomVue" LASIK correction and the advertised
success rates associated with it, I've finally started to evaluate my
suitability for LASER eye correction. My myopia and astigmatism are
both comparatively mild (under -3.5 and -1.05 diopters in both eyes),
but I do have larger than normal pupils (over 7.0 mm). This data is
from one of the initial CustomVue consultations. The system used in
this proceedure is the VISX Star S4 LASER with the CustomVue trimmings
(Orbscan II, etc.).

The VISX Star S4 LASER has a correction field of 6mm and a blend field
of 8mm. Thus, in low light, part of the light passing through my 7+
mm pupil will be less than fully corrected and there is some
possibility of halos due to this undercorrection. During this initial
consultation, I spent 45 minutes talking to the surgeon that would do
the proceedure (which apparently isn't as common as I thought). This
surgeon was highly recommended by co-workers and I was reasonably
impressed with his answers to all my questions. His feeling, based on
previous experience and the smoothness of the blend zone of the Star
S4 laser, was that the difference in correction zone and my low-light
pupil diameter was not a serious source of concern. (A greater level
of testing is done during the actual 2 hour pre-op exam, so neither
one of us had all available information.)

I will be talking to additional surgeons, but can anyone with larger
pupils that has undergone LASIK with a Star S4 LASER (CustomVue or
not) provide any comments on how much of an issue this might be? I've
done quite a bit of web crawling, but does anyone have any pointers to
relevant sites? Are other LASER systems (surgical skill not
withstanding) more suited to people with larger pupils?

Many thanks to all!

-Brian

 

I'm not sure which one is the customvue, but you can look here.
http://www.fda.gov/cdrh/LASIK/lasers.htm

Is it this one?
http://www.fda.gov/cdrh/pdf/p970043s005.html

Look in part 2, but consider these results to be the best possible
results with 6mm pupils only (Unless it explicitly states otherwise).

Just my lay person opinion based on what's happened to me and talking
with others and reading for years on the subject- not a doc. Note
that these results are likely done under the most ideal conditions
where the patients are deliberately cherry picked for best possible
results via rigorous prescreening procedures far and above those done
in standard clinical practice. Then factor in that the Doctors can't
"observe" all the problems that results and patients on average tend
to be happy with vision far inferior (how much no-one knows) to what
they had before surgery.

 

If you do a search of this newsgroup you will find some very heated
debates about pupil size issues.

The safest route is for the optical ablation zone (full correction) to
be equal or greater than the size of your naturally dilated pupils in
a low light environment. If the optical zone is smaller than the
pupil, the probability of night vision problems is at issue. What
greater risk exists (if any) is not reliably predictable. There are
people who have similar circumstances as you who do not have night
vision problems, but then there are those who do.

There are other lasers that have the ability to create a larger
optical ablation zone, however if you desire to keep with a
wavefront-guided ablation, you will find the size of the optical
ablation zone limited. In the future, you can expect approval of
lasers with larger parameters.

Glenn Hagele
Executive Director
Council for Refractive Surgery Quality Assurance
http://www.USAeyes.org
http://www.ComplicatedEyes.org
glenn dot hagele at usaeyes dot org

I am not a doctor.

 

A relatively low amount of myopia and using a blend zone will lead to fewer
night vision disturbances than having a larger amount of myopia and not
using a blend zone, but it would be more desirable to match the pupil and
ablation zone diameter. Perhaps you might want to get another opinion from
someone using the Alcon system.

DrG

wrote in

 

While I'm currently responding to Glenn's post, let me first thank
everyone that has responded - I appreciate it! Further comments
inline below...

So I'm finding as I continue my search!

I've read about occurances of both, but there doesn't seem to be a
strong consensus regarding the cause(s). What has complicated the
issue in my mind are discussions about how Stiles-Crawford effect
negates the need for a correction zone greater than 6mm, provided that
a sufficient blend zone is created. (In addition, the effect seems to
vary depending on whether the obliquely oriented light is hitting rods
or cones on the retina.) While the effect itself seems to have been
originally articulated back in the 1930's, the recent discussions I
have found almost treat it as a new discovery. (I've read some papers
by Holladay, etc.)

Yes, and I'm willing to wait rather than damage my night vision, but
some idea of a timeline would be helpful. Most the new technology
that I have seen discussed involves more complicated procedures, lens
replacement/addition
concepts or other such topics. I haven't seen much regarding advances
in optical zone size and the resolution of night-vision problems in
general.
I'm still searching, but any pointers to such material would be
appreciated.

-Brian

 

Glenn wants you to use a CRSQA surgeon and Dr. G is worried about
liability. My interpretation of what they're saying is that wavefront
LASIK as it is approved by the FDA currently would be EXTREMELY
dangerous for you. LASIK in general is the most dangerous thing that
most of people who have it do in their entire lives, but for you it is
even MORE dangerous because it is NOT FDA approved for your pupil size
apparently.

LASIK also probably increases the risk of cancer, CJD and a number of
other serious life threatening health problems. They'll (other
posters here) try to discredit me, but they won't provide any evidence
to the contrary. I can provide evidence.

If you value your health, do NOT do LASIK or any other elective
surgery.

Michael

 

If you want to have the least bit of credibility, you should stop making
these kinds of comments. If I remember correctly, about 50,000 people die
each year in car accidents. Now THAT'S dangerous. I don't know how many
people die of LASIK each year, but I would guess none.

 

Dr. Holladay is a respected member of our Board of Directors and he
has been at the forefront of the prolate v. oblate cornea debate.

The big issue is that there doesn't seem to be a strong consensus
regarding the cause(s) because no one had been able to totally
determine the cause(s). For that reason, the best that is offered is
the safest route, and all else is an educated guess with the patient
dealing with the consequences.

I loath to predict the FDA, but history shows that optical size
expansion and expansion of the treatable refractive error should be
approved within two years. Some advances are available outside the US
now.

Glenn Hagele
Executive Director
Council for Refractive Surgery Quality Assurance
http://www.USAeyes.org
http://www.ComplicatedEyes.org
glenn dot hagele at usaeyes dot org

I am not a doctor.