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In line phaco-filter aims to improve safety
Barbara Boughton in San Francisco
A new in-line filter made by Staar Surgical Inc permits a distal
constriction that is unlikely to be occluded by nuclear particles,
thus permitting high vacuum levels during phacoemulsification, according
to a presentation at the annual ASCRS Symposium on Cataract, IOL
and Refractive Surgery.
Stephen Bylsma MD presented a study comparing the in-line filter
and standard coiled tubing. In the study, the filter was inserted
into the aspiration line to filter out nuclear particles after they
exited the phaco handpiece. Vacuum was increased to 500 mmHg with
an aspiration of 35 cc/min and compared to standard coiled tubing
at 300 mmHg and aspiration of 30 cc/min using the Wave phaco unit.
The in-line filter was associated with greater anterior chamber
stabilisation despite higher vacuum and aspiration levels. Nuclear
particles were completely captured by the filter, and no cases of
clogging occurred. The effluent from the aspiration line was free
of nuclear particles after surgery.
The new filter allows vacuum levels of up to 500 to 600 mmHg, making
it easier for surgeons to use larger tips and tubing, and improves
the efficiency and safety of cataract surgery, he explained.
"The in-line filter is a relatively simple device, but it completely
eliminates surge even at high vacuum and flow rates," Dr Bylsma
said.
Today's cataract removal technology allows extremely high vacuum
rates, accomplishing much of the important work of cataract surgery-breaking
the bonds of the cataract, and making surgery on dense cataracts
easier, Dr Bylsma noted.
However high vacuum rates depend on a small focal constriction,
which are at greater risk for occlusion, and which gives rise to
occlusion rush. The in-line filter-- also nicknamed 'cruise control'--
is one of two devices that provide passive suppression of occlusion.
The other choice is coiled tubing that creates turbulent flow through
its coils, and passively suppresses surge, Dr Bylsma explained.
"The new in-line filter was nicknamed 'cruise control' because
of the control it gives the surgeon during cataract procedures.
It slows everything down and makes the procedure more stable. It
has a very smooth feel to it."
He recommends using the device once without increasing vacuum levels,
just to get used to operating with the in-line filter, then increasing
vacuum by 25-50 mmHg increments. With the in-line filter, vacuum
levels can go up to 600 mmHg.
"But you really don't need to go that high-450-500 mmHg is
fine. After reaching a high vacuum level, you can then increase
flow."
He noted that the device is disposable and inexpensive, and can
be used with any kind of phaco unit, even Venturi machines. An added
benefit of using the system is that the surgeon can show the patient
what the cataract looked like after surgery.
Dr Bylsma noted that many of the newest phaco machines already have
microsensors built in to correct clogging of the aspiration line.
Thus, the question arises: 'Is the new in-line filter really needed?'
"Just like cruise-control in your automobile, it is possible
to get where you're going without it, but it sure is nice to have
the added safety and control this new device offers," Dr Bylsma
remarked.
Lisa Arbisser MD expressed some doubts:
"I haven't yet tried the filter myself. It is probably not
necessary on the newest generations of machines with their sophisticated
methods of surge protection, but for earlier models it may be very
helpful. I have not been completely satisfied with stability at
500 mmHg however and may find this a useful addition though I'm
concerned about its effect on changing the compliance of the system.
It is intriguing to think of giving this (the nuclear particles)
to the patient at the end of the case so they can have a good idea
of the density of their cataract."
Stephen
S. Bylsma, MD
Shepard Eye Center, Santa Maria, California
sigste@aol.com
Lisa Arbisser MD
Eye Surgeons Associates, Davenport, Iowa, US
drlisa@arbisser.com
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