RETINA SURGERY GLOBAL PERSPECTIVES
Section Editors: Stanislao Rizzo, MD; Albert Augustin, MD;
J. Fernando Arevalo, MD; and Masahito Ohji, MD
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Innovations in27-Gauge Vitrectomy for
Sutureless Microincision
Vitrectomy Surgery
Duty cycle control and dual-port cutters may allow wider use of ultrasmall-gauge vitrectomy.
BY SHUNSUKE OSAWA, MD; AND YUSUKE OSHIMA, MD

T

42 RETINA TODAY JULY/AUGUST 2014

(courtesy of Alcon)

he common thinking regarding surgical wounds isthat “much smaller is much better.” Based on thisconcept, microincision vitrectomy surgery (MIVS)
with 25- or 23-gauge instruments has taken overfrom conventional 20-gauge vitrectomy in many cases, andthe technology has evolved radically during the past severalyears. Along with the development of ergonomic instrumentation and new-generation vitrectomy machines, there
has been a rapid adoption of smaller gauge instrumentation on a global scale over the past several years (Figure 1).
The above-mentioned trends and future perspectives
in modern MIVS led us to initiate a 27-gauge vitrectomy
project in 2007. Development of a 27-gauge chandelier
illumination fiber was the first step.1 After years of strenuous efforts, DORC was the first company to offer a complete 27-gauge vitrectomy system. The preliminary surgicalresults using the first-generation 27-gauge vitrectomy system to treat vitreoretinal diseases were reported in 2010.2
At that time, the system was used only in select cases—
mainly macular disease and simple vitreous hemorrhage—
similar to the situation in the early days of 25-gauge vitrectomy. Nevertheless, both the anatomical and visual results
were very promising. The most remarkable findings werethat there was no need to transition to a larger gauge, nosuturing was required, and no hypotony was observed inany of the study cases.
To explore the potential for more widespread use ofthis ultrasmall-gauge system, its functionalities must beupgraded to treat more challenging conditions, suchas cases of advanced proliferative diabetic retinopathy
and primary rhegmatogenous retinal detachment. The

Figure 1. Global trend in surgeons’ preferences for vitrectomy gauge, 2007-2013.

most critical aspect of 27-gauge vitrectomy that must
be improved is the cutting efficiency of vitreous cutter.
According to the Hagen-Poiseuille law (Figure 2), theflow volume of fluid through a pipe can be increased byincreasing the pressure differences between the ends ofthe pipe and/or by decreasing the coefficient of viscosity. This suggests that the cutting efficiency (vitreousflow) of the 27-gauge vitreous cutter can be improvedby (1) reducing the bite size at higher cut rates todecrease the flow viscosity (resistance) and/or (2) maintaining a longer opening time of the cutting port with amaximum aspiration pressure.
In this article, we describe 2 recently introduced technologies that may help surgeons realize ultrahigh performance with 27-gauge vitrectomy probes.

RETINA SURGERY GLOBAL PERSPECTIVES

Figure 2. Hagen-Poiseuille law defines the flow through atube in terms of flow rate, pressure drop, and resistance toflow. The flow rate in vitreous is proportional to the fourth
power of the inner radius of the tube, aspirating time, andinversely proportional to viscosity and lumen length.
Figure 3. Comparison of flow rates between 27+ and 25+
probes in porcine vitreous.

Figure 4. Comparison of flow rates flow rate in balanced
saline solution and in vitreous among 27+ UltraVit probe andother standard vitrectomy cutters.

DUAL AIR-DRIVEN, DUTY-CYCLE CONTROL
27-GAUGE CUTTERThe Constellation Vision System (Alcon) features adual pneumatic-driven technology enabling ultrahighspeed cutting with duty cycle control. This provides a
promising platform for the development of an efficient
27-gauge vitrectomy system. The company’s 27+ product line features a 27-gauge vitrectomy probe capableof cutting at up to 7500 cpm with a function of duty
cycle control based on cutting rate.
An experimental study compared the practical performance of the UltraVit 27+ cutter in porcine eyeswith that of a 25-gauge cutter (25+; Alcon) with theConstellation Vision System. In this setting, the 27+
cutter showed approximately 60% of the flow efficiency of the 25+ (Figure 3). When compared withthe 25-gauge system at 2500 cpm, the vitreous cutting
flow of 27+ at 7500 cpm with the Constellation Vision
System had better efficiency by approximately 2 times
or more (Figure 4).
The latest addition to the Constellation is a custom-

Figure 5. A proposed 3-D submode setting for efficient vitrectomy. Core vitrectomy is possible with full depression of
the footpedal to maintain maximum aspiration of 650 mm Hg
with higher duty-cycle cutting rate of 5000 cpm, and safer
peripheral vitreous shaving is possible sequentially by releasing the footpedal to obtain proportional control of aspiration
with the highest cutting rate of 7500 cpm.

izable three-dimensional (3-D) submode that allows
the operator to easily switch different cutting andaspiration settings during vitrectomy using the footpedal. For example, it is possible to customize 2 different settings with different cutting rates based on duty
cycle (Figure 5); core vitrectomy is possible with fulldepression of the foot pedal, with maximum aspirationof 650 mm Hg and maximum duty cycle cutting rateof 5000 cpm, and safer peripheral vitreous shaving isachievable sequentially by releasing the foot pedal toobtain proportional control of the aspiration with amaximum cutting rate of 7500 cpm.
This dual setting enables an efficient core vitrectomy
with full pedal depression and safer peripheral shaving
JULY/AUGUST 2014 RETINA TODAY 43

RETINA SURGERY GLOBAL PERSPECTIVES

Figure 6. Another proposed 3-D submode setting for membrane delamination. The 2 cutter settings for membranedissection can be switched and adjusted quickly and sequentially by footpedal control.

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by releasing the foot pedal to allow
proportional control of the aspiration for retinal detachment surgery
with the 27+ system.
A smaller gauge cutter would
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be useful for membrane dissection in diabetic eyes. The 27+ iscurrently the best for this indication because it canbe easily inserted into the tiny spaces between membranes without the need for complex instruments andspecial techniques. To maximize the potential of 27+
for membrane dissection, the treadle control 3-D submode could be used to customize 2 cutter delamination settings for sequential use based on 2 membranedissection techniques first proposed by Steve Charles,
MD.3 The so-called foldback delamination is a usefuland safe technique for removing flexible, weakly fixed
membranes by putting the cutter port just behindthe membrane’s leading edge and folding back themembrane into the port with high-speed cutting inshave mode with gentle aspiration. The membranes
between the cutter port and the retina may reduce thepotential risk of creating iatrogenic breaks. By contrast,
thickened fibrovascular membranes, large blood clots,
and retained lens fragments can be engaged and cut
off with the small-gauge cutter using reduced cut rates.
In the case of thickened membranes, it is preferableto use the conformal cutter delamination technique.
Thickened membranes can be dissected directly bymoving the cutter port forward into the leading edge

Figure 7. Ultra highspeed cutting with a 27+ cutter in an eyewith a massive vitreous hemorrhage (A). Use of this instrumentation allows the surgeon to safely and completely shave
the peripheral retina (B). The small probe can act like a pickand allow the surgeon to lift up abnormal tissue and get into
the space between the proliferative membrane and the retina(C). The 27+ cutter can also act like vertical scissors by cutting
the proliferative membrane safely with efficient segmentation (D).

44 RETINA TODAY JULY/AUGUST 2014

Figure 8. Flow rates in vitreous compared among the27-gauge twin duty cycle (TDC) cutter and other cutters. The
TDC cutter has constant vitreous flow regardless of cutting
rate.

eyetube.netof membranes while adjusting the port away from theretina to reduce the risk of retinal tissue entering theport.
In conjunction with the programming capabilities of theConstellation Vision System, these2 cutter delamination settings
can be customized sequentially(Figure 6). The surgeon can switch
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between the 2 techniques quickly

RETINA SURGERY GLOBAL PERSPECTIVES

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DOUBLE-PORT 27-GAUGE CUTTER
The concept of a double-port cutter, with a second
port in the internal guillotine blade of the cutter, hasbeen proposed. The second port, incorporated into
the pneumatic spring-driven cutter, improves flow
efficiency by allowing the maintenance of duty cycle
without attenuation while cutting rate is increased. The
original idea for this type of cutter received a US patent
more than 20 years ago (Hayafujiet al; 1992).
Because the cutting port wasalmost fully open in this design, it
was not suitable in the 20-gaugeera, because the potential risk ofeyetube.net/?v= iwupe
increasing the tractional force
on the vitreous was a major concern in a cutter witha large inner lumen and low cutting rate. However,
because of the increased cutting efficiency with a smalllumen cutter, as in 25- or 27-gauge instruments,4,5 thepotential risk of tractional forces will be lower, andthe potential to increase cutting efficiency is promising. DORC, in collaboration with Claus Eckardt, MD,
has developed a double-port 27-gauge twin-duty cycle(TDC) cutter with cutting rates of up to 6000 to 8000
cpm.
We carried out a laboratory experiment comparing
the aspiration flow rate in balanced salt solution andporcine vitreous with the 27-gauge TDC cutter withthat of a conventional 27-gauge cutter. As expected,
the flow rate in saline solution remained constantregardless of the cut rates (Figure 8). The aspiration
flow of the 27-gauge TDC cutter in porcine vitreous
was better than that of the standard 27-gauge cutter
by 50% or more and, surprisingly, almost equal to or alittle bit better than that of a standard 25-gauge cutter.
The 27-gauge TDC cutter is very efficient for vitreous
hemorrhage removal and membrane dissection during
diabetic vitrectomy.
EXPANDED SURGICAL INDICATIONS
Similar to 25-gauge instrumentation, when a27-gauge systems first became available, it was suitable only for simpler cases, such as macular surgery
or simple vitreous hemorrhages.2 The latest generation 27-gauge instrumentation can be used for more
complex cases such as rhegmatogenous retinal detachment,6,7 proliferative diabetic retinopathy,8 retained

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lens fragments, and subretinal
hemorrhage.
The latest surgical technologies
and techniques discussed above
have greatly improved the effieyetube.net/?v= eeroh
ciency and safety of 27-gauge vitrectomy systems. Ultrahigh-speed
cutting, duty-cycle control, anddouble-port design are the mostcritical new factors influencing theperformance of 27-gauge cutters.
New generation 27-gauge systems
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will likely enable widespread useof this modality for the full spectrum of vitreoretinal
pathologies in the very near future. neyetube.net

by rotating or repositioning the cutter port whilechanging the pedal depression to select the preferredcutting setting depending on the thickness and fragilityof the fibrovascular membranes (Figure 7).

This article was based in part on a presentation byDr. Oshima at the Chicago Midwest Retina Update 4th
Annual Meeting.
Shunsuke Osawa, MD, is a vice director inthe department of ophthalmology, Okanami
General Hospital in Mie, Japan. He has nofinancial interest in the companies or products
discussed herein. Dr. Osawa may be reached ats.osawa1108@gmail.com.
Yusuke Oshima, MD, is the founder anddirector of Oshima Eye Clinic, a vitreoretinal
and cataract surgery center in Takatsuki,
a consultant and visiting surgeon at theNishikasai Inoue Eye Hospital, a visiting lecturerof ophthalmogy at Kyoto Prefectural Universityof Medicine, Kyoto, all in Japan; and an honorary director of the vitreoretinal division at the Tianjin Eye Hospitaland visiting professor of ophthalmology at the Nankai
University in Tianjin, China. He is a member of the Retina
Today Editorial Board and an editorial member of theRetina Imaging Bank of the American Society of Retina
Specialists. He is a consultant for Synergetics. Dr. Oshima
may be reached at yusukeoshima@gmail.com.
1. Oshima Y, Awh C, Tano Y. Self-retaining 27-gauge transconjunctival chandelier endoillumination for panoramic
viewing during vitreous surgery. Am J Ophthalmolol. 2007;143:166-167.
2. Oshima Y, Wakabayashi T, Sato T, et al. A 27-gauge instrument system for transconjunctival sutureless microincision vitrectomy surgery. Ophthalmology. 2010;117:93-102.
3. Charles S. Fluidics and cutter dynamics. Retinal Physician. 2012;9:58-60.
4. Rizzo S. Performance of a modified vitrectomy probe in small-gauge vitrectomy. Retina Today. September
2011:40-42.
5. Rossi T. New shapes for vitreous cutter blades: A particle image velocimetry study. Paper presented at: American
Society of Retina Specialists annual meeting; August 24-28, 2013; Toronto, Canada.
6. Oshima Y. Continuing development of 27-gauge vitrectomy systems: where are we now? Retinal Physician.
2012;9:20-25.
7. Rizzo S, Barca F. Twenty-seven-gauge sutureless microincision vitrectomy surgery: a new frontier? Retina Today.
April 2013:37-40.
8. Berrocal M. A minimalist approach to surgery for diabetic retinal detachment. Retina Today. 2014;9(3):65-69.

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