Stephen S. Lane, M.D.: Dr. Chang, what is your
interpretation of the definition of bimanual
phaco? Should we call it something different
other than bimanual phaco? I've heard the terms
microincision cataract surgery (MICS) used. I'd
like your opinion as to what it should be called
and what it involves in terms of
instrumentation?
David F. Chang, M.D.:
If the goal is to downsize our phaco incision
size, we have to dissociate the irrigation
sleeve from the aspirating phaco needle. That's
why the term bimanual phacoФ fits pretty well,
because it describes that we're separating the
irrigation and the aspiration instrumentation.
Terms, such as
microincisional cataract surgery (MICS)
highlight the fact that bimanual instrumentation
reduces incision size. However, aside from
incision size, an important question is whether
there are fluidic advantages with this system,
compared to coaxial phaco.
The renewed
interest in this concept was kick-started by the
Sovereign WhiteStar technology (Advanced Medical
Optics, Santa Ana, Calif.) because I think most
of us would have assumed that the real danger in
doing sleeveless phaco was a wound burn.
Part of the impetus
for developing cold phacoФ instrumentation that
is to say technology that gives us a big margin
of error with respect to incisional heat was to
enable us to dissociate the irrigating sleeve.
Surgeons are showing that you can do this with
other phaco machines as well.
Lane: Does anybody else
have anything to add to this in terms of other
instrumentation or other parameters that would
qualify or constitute bimanual phaco?
Mark Packer, M.D.: I
would add some parameter of incision size to
this. If you do a literature search for
bimanual, you end up with articles that discuss
coaxial and the use of a second instrument, as
opposed to one-handed phaco. I think that's a
bit confusing. I think also there's some
implication about incision size sub 1.5. We use
20-gauge instruments and 1.2-mm incisions, but I
think that where there's an implication about
incision size that needs to be some part of the
definition as well.
Roger Steinert, M.D.: I
don't think the term bimanualФ covers it because
that alone doesn't convey what we're talking
about. I think what captures peoples' attention
is the small incision.
Lane: Dr. Mackool, I
know you've discussed cold phaco before. Is it
fair to use the term cold phacoФ for any type of
phaco that we do with ultrasound?
Richard Mackool, M.D.:
There's no question that if you
reduce the duty cycle of any instrument, you'll
decrease the temperature of the instrument. In
other words, it's releasing less energy per unit
of time, so the temperature of that tip is going
to be cooler than one that has a higher duty
cycle.
Having said that, the term
cold phacoФ is absolutely a marketing term. It
doesn't belong in the lexicon of physicists
because phaco isn't cold. Ultrasonic energy is
energy and it will increase the temperature
surrounding the needle.
Lane: Safety is certainly one of the major
issues around any procedure that we're doing.
What are some of the safety concerns surrounding
bimanual cataract surgery?
Packer: I think a large
safety issue has been maintenance of the
chamber.
One of the early
problems that instrument developers encountered
was getting enough irrigation flow into the
chamber to maintain a stable chamber. When you
have a 20-gauge instrument whether it's an
irrigating chopper or an irrigating manipulator
you need as big a lumen as possible to get an
adequate flow in there. That flow needs to be
higher than your aspiration flow, significantly
higher, in order to maintain the chamber.
A large change has
been with instrumentation. Microsurgical
Technologies (Redmond, Wash.), ASICO (Westmont,
Ill.), and Rhein (Tampa, Fla.) have made
irrigating choppers that provide adequate
inflow.
One of the things
that we have to do in order to get adequate flow
is raise the bottle all the way to the ceiling,
or in the case of the Millennium (Bausch &
Lomb, Rochester, N.Y.), which has a module by
which you can pressurize the bottle, use that
feature, and then have the bottle lower.
Chang: The one thing
that has enabled me to use a higher vacuum is
the Cruise Control device from STAAR Surgical
(Monrovia, Calif.). This disposable device can
be attached to any machine's tubing to create a
significant flow restriction that reduces surge.
Steinert: I don't know
that I do anything differently, but I have not
found that the fluidic balance is nearly as
marginal or critical as we have all believed.
I've gone back to 19-gauge. Although I do have
my bottle height very high and I try very hard
not to have excessively large incisions, I have
not found chamber fluctuation to be a
particularly big issue, at least with the
Sovereign unit (AMO). Going back to 19-gauge
bimanual has not slowed me down.
Lane: Do you feel that
bimanual phaco right now is as efficient as
coaxial phaco?
Steinert: Yes, if I use
19-gauge.
Lane: So the time
period that it would take you to do a typical
case is roughly the same amount of time that it
would take you to do if it were a coaxial case?
Steinert: Yes. And
perhaps even faster because I do think that the
bimanual instrumentation, if it's optimized,
actually gives you more control in terms of
maneuverability of the fragments. The key is to
be truly bimanual.
Lane: Dr. Mackool, tell
me about efficiency? What are the drawbacks with
the bimanual phaco as opposed to coaxial?
Mackool: I find that I
am currently slower with the bimanual technique,
compared to the coaxial technique. I can perform
bimanual with the Alcon Legacy AdvanTec using 40
cc a minute flow rate and 250 mm of vacuum. With
the Infiniti, I would look at about the same
flow rate and a higher vacuum level of 400 mm Hg
for nuclear segment removal. It is possible to
use the higher vacuum level with the Infiniti
because of the reduced compliance in the
aspiration component of this system.
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do the bimanual procedure in a reasonable period
of time. However, it requires more manipulation
and searching movements with the left hand to
position infusion appropriately. This is
particularly true with infusion choppers that
deliver the infusion in a coaxial fashion (i.e.
fluid exits directly out of the end of the tip).
When using choppers that permit the fluid to
exit perpendicularly to the axis of the tip,
infusion is delivered over a wider area and
there is less need to continuously reposition
the location of the infusion chopper.
There is no
comparison between the amount of fluid that is
generally required for the bimanual procedure
compared to the coaxial procedure.
Currently, my phaco
incision during the coaxial procedure is sealed
(I use the Mackool hand piece by Alcon), and
therefore there is no incision leakage around
the phaco tip. My side port incision is very
tiny (about 0.5 mm external incision and 0.25 mm
internal incision, tapered), so there is minimal
leakage from the side port incision.
The net result of
this is that I remove the nucleus using only
13-31 cc of fluid with the coaxial technique.
With leaking bimanual incisions, coupled with
the fact that lower vacuum levels are used and
nucleus removal therefore takes longer, it is
virtually impossible to use less than 100 cc for
nucleus removal at the present time.
Lane: Dr. Steinert, do
you find that you're using more irrigation fluid
with bimanual than you do with coaxial?
Steinert: No, I don't.
I think that's an incision size leakage issue.
Lane: And, Dr. Mackool,
you use Mackool needles (Alcon) to allow for a
tight coaxial incision, correct?
Mackool: Yes. I'm using
a 1.1 Mackool flare tip through a 2.75-mm side
incision. The side port incision is just about
0.5 mm. It is actually tapered, so it's a real
tiny side port that's hardly leaking.
Lane: I think you'll
find that you're going to, by the nature of
making these tight incisions for bimanual,
reduce your overall fluid usage.
Mackool: I would agree.
Compared to the 3.2-mm phaco incision of the
past that would leak 20cc, 25cc a minute, and
required the surgeon to change the bottle during
most cases, we are doing much better. The
literature typically reported surgeons using
250-350cc used per case. We could do 10 patients
with that amount of fluid today.
Chang: Dr. Lane, if you
had asked me this question a year ago, I would
have said, hands down bimanual takes longer.
Beyond the
increased operative time, having to turn my
aspiration flow and vacuum rates down, was a
real tradeoff and disadvantage. But again, since
I have been able to work at my usual high vacuum
rates with the Cruise Control device, the
fluidic gap has closed considerably.
I would still say that
overall, coaxial phaco is just a little bit
faster in my hands. As an analogy, bimanual I/A
is available to all of us as well. But most
people prefer coaxial I/A, probably because it's
a little bit faster, and provides a higher
infusion rate.
The one thing that
still bothers me the most is that the chopper is
more constrained when we're doing bimanual
phaco. It has a much broader shaft, there's more
tendency for oar locking, and it's somewhat
tethered by having the tubing attached to the
end of it. So I think that slows me down a
little bit in terms of efficiency and speed.
Lane: Dr. Packer, do
you want to speak to efficiency?
Packer: In terms of the
total amount of time that the case takes me now
that I've done this for over a year, it's
identical to the time that I was taking before
with coaxial. So the overall operating time is
unchanged.
I have seen a
reduction in effective phaco times. We're
collecting this data now, and I know there are
all kinds of questions that come up, such as
stratification of data by grade of nucleus, etc.
But we will have
all that information and right now, looking at
early numbers, we will have further reduced
effective phaco time by using this procedure
compared with the same technology with coaxial.
And, as you know,
we've shown that reduction of effective phaco
time is one of the most important things you can
do to make sure you have a clear cornea and good
visual acuity the first day. But when I think of
efficiency, I really think about what I have to
do to get the outcome I want. And what I want is
a happy patient on day one. And I think that I'm
doing better now with bimanual than I was doing
with coaxial before, and that's one of the
reasons why I've stuck with it, and why I like
it.
Lane: I think you're
right. Dr. Packer had brought up the point that
efficiency certainly means much more than time.
And so I use time as just one barometer of
efficiency.
One of the things that
troubled me, as I started doing bimanual
microincision phaco, is really the position of
the irrigating chopper, if you're using a
chopper.
Dr. Mackool's point
was absolutely right about that. You find
yourself chasing things a little bit more
because the inflow coming from that needle tends
to push pieces it away from your phaco tip much
more than coaxial does.
And so your
positioning of that second instrument is
critical to avoid pushing that piece away and
having it washing around the anterior chamber as
you're trying to get a hold of it, regardless of
your fluidics setting. So one tip for those that
are starting this is to pay attention to that
and determine how to position that second
instrument. It takes a while to catch on and
refine your technique.
Packer: I think that
that is a critical point. Really, that stream of
irrigation fluid is another instrument now in
the eye. It's something we never had before. We
now have control of inflow. And one of the
things that I noticed right away was you get a
nice piece right on your tip and the next thing
you know it's shot over into the angle because
you blew it away with your stream of irrigation.
So what I've tended
to do is to have the aspiration and irrigation
tip in different planes, or at least directed in
different directions. And it's not always
obvious from watching surgical video, because
you don't have the stereopsis that you do
through the microscope. But keeping the
irrigating chopper further posterior and the
aspirator in, say, the iris plane, is one
technique for making sure that the stream
doesn't knock the material off.
I also like to
rotate my chopper horizontally when I get down
to the epinucleus, so that that sharp element is
no longer directed toward the capsule, but is
horizontal. That way, I can actually direct the
stream of fluid posteriorly to help inflate the
capsule and keep it on-stretch. That facilitates
trimming and rotating the epinucleus. You can
actually use the phaco needle to rotate the
epinucleus, or you can use the blunt end with
irrigation fluid coming out, because you know
that flow is keeping the capsule away.
Steinert: At the
beginning, I would find that I always had at
least one nuclear chip kind of plugged against
the outflow, and it was very annoying to me. I'm
working with a couple of the companies on
changing from this end opening irrigant outflow
on the chopper to going back to the side
outflow, because I think that that will solve a
lot of these issues.
I think personally,
at least with my technique, that I need two
instruments, not one. When I chop, I typically
use my clawed chopper to break up the nuclear
particles.
When I get down to
my last particle and I'm in danger of the
posterior capsule starting to come forward, I
always switch with coaxial phaco to a second
instrument, which is much more of a
capsular-friendly spatula type instrument in
order to manipulate the epinucleus. Everybody
has a different way of approaching these
challenges.
I think we're going
to see a rapid evolution, just as we did in 1993
when Nagahara introduced phaco chop. I think
we're going to see things kind of gel toward a
more consistent approach and it will solve most
of the issues you're bringing up.
Lane: Dr. Packer
mentioned capsulorhexis. Dr. Steinert, do you
want to just talk briefly about how you handle a
capsulorhexis through those small incisions?
Steinert: Earlier we
mentioned the oar lock and that is really a key
issue with bimanual phaco. We are talking about
very small incisions. And for those of us that
work with residents that are learning cataract
surgery, the very first thing you have to get
through to them is the concept of an oar lock.
I've found with the
very first rhexis forceps that we designed for
this was that I was getting hung up at the
incision by the outer leaf, should we say, and
that would get hung up right at the Descemet's
entry point where the rhexis was closest to the
incision. But I think a couple of the companies'
products I've had chance to use do a very good
job at solving that problem.
Those products have
better tapers and shorten the distance between
where the grabbing teeth are and the end of that
outer sleeve. As long as you keep that distance
short, you don't get hung up.
The payoff is that
you have better maintenance in the anterior
chamber. And quite frankly, if I didn't need
viscoelastic for the injector of the IOL, I
don't think I would use it on most cases at all.
You can use infusion capsulorhexis forceps now
that will maintain your anterior chamber in an
exquisite fashion.
Chang: I actually use a
bent 25-gauge needle as an irrigating cystotome
without any viscoelastic for the capsulotomy,
and I think people can teach themselves to do
that during routine coaxial phaco cases.
I would tense the
globe with 1% lidocaine to facilitate a standard
clear cornea keratome incision. The irrigating
cystotome is introduced through a separate
paracentesis. If there is a problem controlling
the tear, you can always inject viscoelastic and
finish the capsulorhexis with forceps through
the standard incision.
There is an
advantage to performing the capsulorhexis
without viscoelastic when working through
microincisions. One problem we haven't talked
about is that after a forceps capsulorhexis, you
usually have a chamber filled with viscoelastic
and you have to be very cautious when
hydrodissecting through a microincision.
Compared to a
standard phaco incision, it won't decompress as
quickly and as easily during hydrodissection and
you may hyper inflate the anterior chamber in
the process.
However, if you can
complete the capsulorhexis with an irrigating
cystotome without viscoelastic, you can insert
the hydrodissection cannula through the
paracentesis, and shallow the chamber by
depressing the shaft slightly. Then you can
safely inject the necessary amount of fluid to
hydrodissect and spin the nucleus without
suddenly over-expanding the chamber.
Lane: Let me play
Devil's advocate here. At this point we don't
have a lens approved in the United States that
will fit through an incision that's as small as
1.5 mm or 1.2 mm in some of your cases. And so
if that means we're back to the old days where
we all remember when foldable lenses were en
vogue, and we were doing phaco through a 3-mm or
3.2-mm incision and then opening it to 5.5 mm or
6 mm to put a PMMA lens in. Why should we be
working on this? Why should we be doing
small-incision bimanual phaco when we, indeed,
have to open the wound up to put a lens in
anyway?
Packer: While we don't
have all the hard data in yet to say whether
that's really the case or not, my feeling right
now is that this is really a superior procedure.
I want to continue doing it, long enough at
least to find out for sure.
Mackool: The question really now begins to boil
down to Are there intra-operative advantages?Ф
Dr. Packer seems to believe that he's found
some. Frankly, I have not yet been able to do
so. It's slower, and I'd like to say that I
could find some and I'm still trying to find
some, but I can't.
Should we probe,
should we push, should we look? Yes. But should
we come right out and say to everybody this is
the future of cataract surgery? I think we would
be in danger of overstepping our knowledge at
the present time if we did that.
Lane: There's been
implications that you have to have certain types
of machines that will be able to do this and you
might not be able to do it with some of the
older equipment. Can somebody address those
issues? Can you, for example, do good bimanual
microincision phaco using a Legacy instead of an
Infiniti or instead of a WhiteStar?
Packer: Yes, it can be
done with a Legacy. We've done it with the
Infiniti, with the Sovereign, with the STAAR
Sonic Wave, and with the Millennium. Any of
these machines can be set up to perform safe and
efficient microincision phaco.
It's clear you
don't absolutely need any special capsulorhexis
instrumentation to do this. We started with a
bent needle. The first ones I did were that way,
but I like starting with a pinch because I think
there's better control.
So anyway, you
should add a pair of capsulorhexis forceps. And
then the main point is that you need to have a
set of irrigating second instruments.
Microsurgical Technology manufactures the Duet
System, which includes a variety of front and
side irrigating choppers and manipulators. ASICO
makes side-irrigating choppers in a variety of
styles.
And another thing
that people might not think about is that you
need to have a short sleeve on your phaco tip
because there will be a lot of spray and outflow
to wet your sleeve as you're operating.
Chang: The first thing
is to get a bimanual I/A set and practice
cortical cleanup with this setup for routine
cases. It's important to get used to working
through bimanual incisions, if you haven't
already done that.
Next, don't try to
do every step through a 1.2-mm incision. Because
you need it for the IOL anyway, make and use
your standard cataract incision for the
capsulorhexis and hydrodissection. This allows
you to evaluate and experiment with bimanual
phaco instrumentation without the additional
constraints of using a paracentesis for every
step. As far as purchasing additional
instruments, you mainly need to get an
irrigating chopper.
As Dr. Packer said,
MST provides many different interchangeable
tips, and you can change the tips if you don't
like the one you have. One place people might be
tempted to cut corners is with using a
Superblade to freehand the incision. You should
obtain a metal keratome specifically sized for
1.2 mm.Otherwise, with free hand incisions, you
never know from one case to the next how much
the variability in chamber stability was from
your incision size being a little larger or
smaller.
Mackool: Dr. Lane, one
word of caution to folks trying this early on:
They shouldn't presume that because you make a
one point something incision that it's perfectly
sealed right away. These short incisions that
have been deformed into a circle by a round
metallic instrument can leak, and you may have
to hydrate them and check them carefully.
Incisions need to
be sealed at the end of the case. I would say to
you that no matter what way you do them,
bimanual or coaxial, you need to be sure they're
sealed.
Lane: If I was a
surgeon doing very successful coaxial
phacoemulsification, would any of you tell me
that I'm behind the learning curve in terms of
what's going on now with bimanual phaco?
Chang: In my opinion,
there is certainly no need to learn bimanual
phaco now, because there are no clear advantages
at this time. In terms of eventually being
prepared to make the transition, I think it is
extremely helpful to be proficient with phaco
chop. We haven't talked about that, but I would
venture that most people that regularly perform
bimanual microincisional phaco are chopping,
because it is the ideal technique for this.
In addition, if you
are comfortable with chopping, then you already
possess excellent bimanual skills, and the
bimanual phaco learning curve will be much
easier.
Lane: Where do you see
this going in the future?
Mackool: In the final
analysis, I think what will drive what we do is
the best IOL. If the best multifocal IOL, for
argument's sake, happens to require a two-point
something incision, then you can bet there
aren't going to be a lot of people doing two
smaller incisions and then enlarging it.
The IOL is the big
driver here. If we can get our patients to see
better distance, near, and perhaps intermediate,
with one IOL, if that IOL required a 5-mm
incision today there would probably be a lot of
those IOLs being inserted.
Steinert: Well, that's
absolutely true. The IOL is going to be the
final common pathway. But I strongly suspect
that it won't be too long before we deal with
3-mm incision as archaic and just as
unacceptable as a gaping extracap incision. So
it's not wrong, it's not incumbent on anybody to
get into this now, but if you don't want to be
left behind you've got to at least, try bimanual
I/A. And number two, really start getting into
phaco chop.
Mackool: The fact that
the bimanual procedure will require surgeons to
master the phaco chop technique may turn out to
be one of the greatest benefits of the bimanual
procedure.
Contact
Information Gossman: 320-253-3637, fax
320-253-5412, mvgossman@astound.net Nichamin:
814-849-8344, fax 814-849-7130, nichamin@laureleye.com |