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

Single blade cutter

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

40 ml

35 ml

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0 cpm 300 cpm 500 cpm 1000 cpm 1500 cpm 2000 cpm 2500 cpm

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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