Vitreous cutters for small incision Pars Plana Vitrectomy ...€¦ · 15 ml 10 ml 0 cpm 300 cpm 500...
Transcript of Vitreous cutters for small incision Pars Plana Vitrectomy ...€¦ · 15 ml 10 ml 0 cpm 300 cpm 500...
Get into Pole Position
Since the invention of pars plana vitrectomy by Robert Machemer1 in
1969, the complexity not only of the vitrectomy devices, but also of the
vitreous cutters has grown considerably. Due to small incision vitrectomy,
which was introduced by Gildo Fujii2 in 2002, the vitrectomy procedure
became gentler for the patient. At the same time, from the instruments,
which diminished in size, new challenges emerged to the surgeons
and the instrumentarium with reference to surgical strategy, stability of
instruments, cut rate and quality, as well as aspiration performance of
the system surgical device and vitreous cutter s ystem.
For the surgeon the tractive strain to the retina is the most important
and visible influence during the surgical procedure. The most feared
complication during vitrectomy, which is associated to traction, is an
undiagnosed micro foramen in the thin peripheral retina with a secon-
dary retinal detachment.
For this reason vitrectomy devices today are equipped with complex
aspiration systems and optimized duty-cycle-managements for the
control of the vitreous cutter or are operated with oversize instruments.
However, Hagen-Poiseuille’s law3 persists, in which the radius is entered
into the equation in the fourth degree, and with that as the most impor-
tant variable, and so the dynamic viscosity gains importance for a well
functioning vitreous cutter.
With the development of the double blade vitreous cutter some of the
above mentioned device characteristics shrink in importance, without
admittedly sinking into insignificance. The double blade vitreous cutters
improve considerably the performance of the systems for small incision
vitrectomy. Especially the aspiration flow benefits from that. As the guil-
lotine blade carries out two cuts per work step, the vitreous is cut into
smaller pieces compared to coventional cutters. These smaller pieces
can now be aspirated more easily, especially by vitreous cutters with
small lumina, what results in a higher and more permanent flow (fig. 1).
Admittedly this does not abrogate Hagen-Poiseuille, but it does improve
the fluidics of the system’s surgical device and vitreous cutter system and
reduces the dynamic viscosity η with the result of a significantly better
aspiration flow. As a positive side effect the durability of the blades is
increased in comparison to single blade vitreous cutters, what becomes
particularly evident with more complex indications like traumata, orga-
nized vitreous, vitreous hemorrhage or luxated lenses.
www.Geuder.com
Norbert Schrage, MD, Professor, Chief Physician
at the Eye Clinic Köln-Merheim;
Julius Müller-Albinus, GEUDER AG
mach2 double blade Vitreous cutter oVercomes the limits of PreVious Vitreous cutters for small incision Pars Plana Vitrectomy
uno colorline mach 2
Geuder clinical rePort
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Average infusion pressure
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Double bladecutter
Average aspiration � ow
Figure 1: Fluid movement of different vitreous cutter types
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Get into Pole Position
Besides the extremely high cut rates and the safe and fast cutting of
the vitreous, the virtually complete immobility of the retina, even when
cutting near the retina periphery, is remarkable. This cutting smoothness
is, compared to single blade vitreous cutters, an outstanding characteri-
stic of the dual cut with high cut rate.
When using single blade vitreous cutters the surgeon must control two
interdependent parameters, the vacuum respectively the flow and the
cut rate. The higher the cut rate, the lower the aspiration flow because
the aspiration window is, cumulated over time, closed longer. With the
MACH2 double blade vitreous cutter the aspiration window remains
permanently open and decouples the cut rate from the aspiration flow
(figs. 2 & 3). This enables the separate control of these two important
surgery parameters. The result is a faster core vitrectomy and a better
controllable vitreous shaving.
These two characteristics of the MACH2 double blade vitreous cutter,
its ability to cut the vitreous into smallest pieces and to make the flow
directly controllable due to the permanently open aspiration window,
constitute a significant enhancement of the device / vitreous cutter
system.
Literature:
1 Machemer R., & Hickingbotham D. (1985). The three-port microcannular system for closed vitrectomy. Am J Ophthalmol, Vol. 100, (October 1985), pp. (590-592), 0002-9394
2 Fujii GY, de Juan E. Jr, Humayun MS, Pieramici, DJ, Chang, TS, Awh, C., Ng, E., Barnes, A., Wu, SL, & Sommerville, DN. (2002) A new 25-gauge instrument system for
transconjunctival sutureless vitrectomy surgery. Ophthalmology, Vol. 109, No. 10, (October 2002), pp. (1807-12), 0161-6420
3 The American Heritage Medical Dictionary 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company
www.Geuder.com
Figure 3: Aspiration window of a double blade cutter
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Aspiration Flow
Spring driven single blade 23G Spring driven single blade 20GUNO Colorline Mach2 23G
Figure 2: Aspiration flow of different vitreous cutter types
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