The Sovereign (Allergan,
Irvine, Calif.) merges the advanced high vacuum fluidics of the AMO Prestige
unit (Allergan) with the burst and occlusion mode programmability of the
AMO Diplomax (Allergan). Surgeons with Sovereign experience were impressed
by the machines power, programmable settings, fluidics, ease of
use and setup.
The Sovereign has
an on-board fluidic computer that allows the pump to rotate forward and
backward, which helps surgeons to control the release of vacuum. The machine
has several settings for pre- and post-occlusion, four phaco modes and
four memory modes. The four power modes allow surgeons to have continuous
mode phaco, pulse, power pulse and burst mode. Surgeons can use different
combinations of memory to disassemble different types of cataracts.
The small, lightweight,
ergonomic handpiece has four crystals allowing for short, long, multiple
and continuous bursts, in addition to an on/off burst that can be as short
as 20 msec.
David F. Chang, MD,
used the Sovereign to perform both the classic Nagahara and the Pfeifer
Quick Chop variations of phaco chop on a series of 12 brunescent nuclei.
Both of these techniques allow us to decrease phaco power and time
because we are substituting manual energy for ultrasound energy in the
disassembly of the nucleus. We can decrease stress on the capsule and
zonules because the manual forces of one instrument pushing against the
other are directed centrally inward, rather than outward toward the capsule,
Dr. Chang said.
Phaco chop
of dense nuclei is facilitated by achieving a solid purchase of nuclear
segments with the phaco tip. This stabilizes and anchors the nucleus during
chopping and creates enough holding force to elevate chopped pieces out
of the tight confines of the capsular bag. With the Sovereign, solid purchase
of nuclear segments was consistently achieved through the combination
of burst mode, very high vacuum settings and rapid vacuum rise time obtainable
through occlusion mode programmability, he said.
Burst mode, although
inappropriate for a soft nucleus, is very useful for dense nuclei. In
these lenses, it is difficult to keep the tip tightly embedded and occluded.
Burst mode impales the nucleus with single burst strokes that maintain
a tight seal around the tip. Vacuum settings of up to 350 mm Hg (19-gauge
tip) and 400 to 450 mm Hg (20-gauge tip) provided excellent holding force
with a stable chamber, according to Dr. Chang.
The Sovereign cuts
very efficiently at power levels as low as 5% for average nuclei. Low
power levels decrease the stroke length of the phaco tip, reducing chatter
and the amount of heat generated. Because of this, Dr. Chang said, the
average equivalent phaco time for these 12 nuclei was 12.5 seconds (range
of 8 to 21 seconds) using phaco chop.
We found the
Sovereign to be significantly better than any other system we were using,
said Pierre Faber, MD. The cutting of this machine is outstanding,
smooth and powerful. Dr. Faber evaluated the performance and reliability
of the Sovereign and was impressed by the machines fluidics.
The system
[Sovereign] seems to know when occlusion is happening, knows when occlusion
is breaking, so there are no surges, Dr. Faber said. The chamber
is always deep, there is no flattening of the chamber, very little or
no iris flutter, smooth cortical cleanup and disassembly, and it is very
easy to remove the epinucleus.
Concentrix pump versatility
---The
Concentrix can
either replace or coexist with the Millenniums Venturi module.
The Millenniums
Concentrix technology (Bausch & Lomb Surgical, St. Louis, Mo.) is
the only machine to offer the ability to switch between flow-based (peristaltic
like) and vacuum-based (Venturi like) memory settings to best match each
step of a cataract procedure. The Concentrix Fluidics Control Technology
is based on the scroll pump, which consists of two scroll-shaped components.
The female scroll consists of a groove that is stationary. The male scroll
fits inside the female and goes through an orbital motion to create the
vacuum and flow characteristics of the pump. Fluid from the handpiece
passes through a vacuum sensor adjoining to the scroll elements. This
sensor creates a feedback loop to the computer that controls the pumps
speed and direction to give priority to either the flow-based emptying
phase or the vacuum-based filling phase of the pumps cycle, and
create either peristaltic or Venturi like responses. Surgeons then can
establish individual memory settings for each step of a procedure and
program flow-based or vacuum-based modes to maximize the safety and efficiency
of the surgery.
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If we were
doing a divide and conquer technique, we might use a flow mode for sculpting
to give us precise flow when working near the capsule, said Terence
M. Devine, MD. Then we might switch to a vacuum mode to draw out
the quadrants. I think that most surgeons that have used the machine agree
that a Venturi type of vacuum response works best for removing cortex.
But for capsule polishing, a flow mode is probably better. According
to Dr. Devine, vacuum mode is most effective in removing viscoelastics.
The advantages of
the Concentrix Fluidic Control Technology are the simultaneous control
of fluidics and ultrasound with the Dual-Linear Footcontroller, and the
ability to switch back and forth between flow modes or vacuum modes during
a single case. When we combine Concentrix with the Dual-Linear Footcontroller,
I think we gain the benefit of total control of fluidics with more surgical
options, Dr. Devine said. And in the 9 months or so that Ive
been using this technology, it has translated into better safety and shorter
case times.
Infusion capacity improvement
---The
Alcon Accurus.
Pressurized infusion system eliminates the need for infusion bottle elevation.
The Accurus 600DS (Alcon,
Fort Worth, Texas) is an efficient phaco machine that has demonstrated
ultra-rapid nucleus removal while chambers remain stable, according to
Richard J. Mackool, MD. The Accurus is a Venturi system with aspirated
fluid drain and vented gas force infusion, which creates an incredible
improvement in infusion capacity, according to Dr. Mackool.
In my opinion,
vented gas force infusion is better than gravitational infusion,
Dr. Mackool said. It gives more of a consistent chamber depth, and
it is not affected by bottle volume and resistance to air flow by the
bottle spike vent.
Although conventional
gravity feed has been the standard, Dr. Mackool said it is not the best
because of the resistance to atmospheric air flow into the infusion bottle.
The more fluid in the bottle, the harder it is for the air bubble to get
to the top, therefore when the bottle is full, it is difficult to get
maximum infusion capacity. When the bottle becomes less full, infusion
capacity improves. Vented gas force infusion provides reliable infusion
with constant pressure, regardless of bottle volume.
The aspiration cassette
of the Accurus has a tiny 16-cc air space and fluid is maintained at a
constant level in the cassette by a peristaltic vacuum system that drains
the cassette when an optical sensor detects an elevation of the cassette
fluid level. There is a consistent rise time from beginning to end of
cases, according to Dr. Mackool, because the volume of air in the cassette
remains constant.
Efficiency in sculpting
the nucleus was affected by needle design and diameter, especially with
regard to sculpting efficiency in hard nuclei. The nucleus was removed
at a rapid rate without increased risk of chamber collapse or trauma to
the posterior capsule and/or iris.
---The
Kelman-Mackool ABS
Flare Tip.
The Accurus Venturi
aspiration system achieves remarkable levels of aspiration efficiency
and nuclear followability, Dr. Mackool said. [There is] great
efficiency because of in creased nuclear attraction, increased holdability,
rapid nucleus removal and the most stable chambers you could ever imagine.
The phaco tip remains in the safe control zone, and there is maximal thermal
protection with the Mackool ABS flare tip.
Series 20000 Legacy
The Series 20000
Legacy (Alcon) represents one of the new generations of phacoemulsification
systems that debuted during the mid-1990s and has since been updated.
With respect to fluidics,
it has a pump system called TurboStaltic pump that is a very smooth system,
according to I. Howard Fine, MD. It has a floating head so there
are no pulsations as the pump speed and vacuum build-up takes place. It
has non-compliant fluidic channels to allow for higher vacuum with fewer
pulsations, he said.
The tubing
in the cassette has been replaced with rigid plastic fluidic channels
that are totally non-compliant. This allows us to have a high-vacuum system
with less surge. The new high-vacuum tubing allows us to use extremely
high vacuums that were previously considered unsafe, Dr. Fine said.
The ultrasonic generator is a four crystal system, which is extremely
powerful.
The Legacy has constant
admittance tuning, allowing for continuous feedback and re-tuning on a
rapid, ongoing basis. This compensates for changing density and configuration
of nuclear material at the tip in order for the system to work at its
maximum efficiency.
Alcon has recently
enhanced the software, what they call the performance option package.
This software package expands the number of ultrasound modes and the different
ways in which phaco energy can be delivered. It has added enormously
sophisticated power modulations, Dr. Fine said. In the package,
they have added not only burst mode, but variations of burst mode, such
as single burst mode, programmable intervals between bursts, as well as
durations of bursts. In pulse mode, what we have is a distribution of
on/off with equal periods of on and off. When Im in pulse mode,
I usually use two pulses per second, which means I get 250 msec of power,
250 msec on, 250 msec off. Users have a fixed interval of power
and a fixed interval of pause between power while constant vacuum is ongoing.
The vacuum holds, but surgeons will have the ability to vary power.
In burst mode, we
have panel control of power. When the foot pedal is pressed on foot position
3, the interval between bursts of power can be varied. The further the
foot pedal is pressed, the shorter the interval is between bursts. Burst
mode is best used for lollipopping or impaling the nucleus and to evacuate
nuclear material following chopping.
For
Your Information:
- David F. Chang,
MD, can be reached at 762 Altos Oaks Drive, Ste. 1, Los Altos, CA
94024; (650) 948-9123; fax: (650) 948-0563. Dr. Chang has no direct
financial interest in any of the products mentioned in this article.
He is a paid consultant for Allergan.
- Terence M. Devine,
MD, can be reached at RD 2 Box 184E, Athens, PA 18810; (570) 888-5858;
fax: (570) 882-3411. Dr. Devine has no direct financial interest in
any of the products mentioned in this article. He is a paid consultant
for Bausch & Lomb.
- Pierre Faber,
MD, can be reached at 616-2525 Willow St., Vancouver, British Columbia
V5Z 2NB; (604) 879-0203; fax: (604) 879-9976. Dr. Faber has no direct
financial interest in any of the products mentioned in this article,
nor is he a paid consultant for any companies mentioned.
- I. Howard Fine,
MD, can be reached at 1550 Oak St., Ste. 5, Eugene, OR 97401; (541)
687-2110; fax: (541) 484-3883. Dr. Fine has no direct financial interest
in any of the products mentioned in this article, nor is he a paid
consultant for any companies mentioned.
- Richard J. Mackool,
MD, can be reached at 31-27 41st St., Astoria, NY 11103; (718) 728-3400;
fax: (718) 728-4882. Dr. Mackool has a direct financial interest in
the Mackool System. He is a paid consultant for Alcon.
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