The 27-Gauge Revolution
The trend toward smaller surgical instruments has led most recently to the creation of 27-gauge surgery. But is it the be-all and end-all?
The smallest commercially available instrumentation for pars plana vitrectomy (PPV) is 27 gauge.1,2 An increasing number of clinical series have been published on its use,3-5 even in complex cases such as proliferative vitreoretinopathy (PVR) requiring silicone oil placement.6 Since initial feasibility and safety studies were published in 2010,2 an ever-increasing amount of data is available for retina specialists to evaluate this exciting new evolution in vitreoretinal surgery.
AT A GLANCE
• A primary criticism of 23- and 25-gauge vitrectomy is that sclerotomies performed with systems in these gauges do not seal completely, which can lead to hypotony and increased risk of endophthalmitis.
• Use of 27-gauge surgery has been described for even the most complex vitreoretinal surgical procedures; however, there is a learning curve.
• New platforms and further enhancements to instrument design and efficiency will be needed to foster increased adoption of 27-gauge surgery.
In the United States, 27-gauge vitrectomy packs are available for the Eva vitrectomy system (Dutch Ophthalmic USA) and the Constellation Vision System (Alcon). Bausch + Lomb is developing a 27-gauge platform for its Stellaris PC Vision Enhancement System, which it plans to roll out in the first half of 2017. Interested readers can learn more about these vitrectomy systems at bit.ly/vitsystems. This article examines 27-gauge systems and instruments and their applications in vitreoretinal surgery.
PROS AND CONS OF VITRECTOMY GAUGES
Since the introduction of 25-gauge vitrectomy by de Juan and colleagues7 more than a decade ago, the dogma of smaller is better has been reflected in the rise of microincisional vitrectomy and the near extinction of 20-gauge vitrectomy. It is important to remember that the shortcomings of the initial 25-gauge vitrectomy platforms, such as increased vitrectomy times and excessive instrument flexibility, led to the development and use of 23-gauge vitrectomy systems,8 raising the question of whether smaller really is better.
Watch it Now
Video 1. 27-Gauge Scleral Fixation of IOL With Gore-Tex Suture
Michael A. Klufas, MD, and Pradeep S. Prasad, MD, use the Eva vitrectomy system to fixate an IOL to the sclera with PTFE Gore-Tex suture.
A primary criticism of 23- and 25-gauge vitrectomy is that sclerotomies performed with systems in these gauges do not seal completely, which can lead to hypotony, choroidal detachment, and endophthalmitis. Decreasing the gauge size to 27 gauge (0.4 mm) has the potential to decrease the rate of these complications.1 However, initial clinical series show that, even with 27-gauge incisions, suturing of sclerotomies may be necessary and hypotony is still possible.3 In vitro studies with human cadaveric eyes have suggested that nonbeveled 27-gauge incisions are less likely to allow bacteria to enter the eye compared with 23-gauge nonbeveled sclerotomy incisions.9 A prospective study comparing 25-gauge versus 27-gauge vitrectomy evaluated sclerotomy incision via anterior segment optical coherence tomography (OCT) and found no difference in the mean time to scleral wound closure (8.6 vs 7.7 weeks).10
There is no way around it: it will take longer to remove the vitreous with smaller 27-gauge instrumentation than with 23- or 25-gauge cutters. One of the key metrics of vitrectomy efficiency is flow rate, which is proportional to aspiration force, the fourth power of the radius, cut rate, and duty cycle; and inversely proportional to cutter length and the viscosity of the medium being removed.1,11-13 Oshima and colleagues have reported that the 27+ vitrectomy cutter (Alcon) showed approximately 60% the efficiency of the 25+ vitreous cutter (Alcon) at 7,500 cuts per minute (cpm).1 A clinical study with the Eva TDC cutter (Dutch Ophthalmic USA) found that mean core vitrectomy time was 73.80 seconds for 25 gauge and 159.71 seconds for 27 gauge.11 The same core vitrectomy with a standard non-TDC Dutch Ophthalmic USA 27-gauge vitreous cutter was 242.71 seconds.11
Despite these increased times, the fluidics of vitreous cutters are noteworthy. The Eva 27-gauge TDC cutter is capable of removing half of a nucleus from the posterior segment without the need for a traditional fragmatome.14 In fact, the aspiration of that 27-gauge cutter is equal to or greater than that of a standard non-TDC 25-gauge cutter.
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Video 2. 27-Gauge PPV With Membrane Peel
During this 6-minute procedure by Michael A. Klufas, MD, and Steven D. Schwartz, MD, ILM forceps were inserted through a 27-gauge trocar and were used to remove a macular pucker in a 48-year-old man with progressively decreasing vision and metamorphopsia after silicone oil removal and cataract extraction with IOL placement.
The rigidity of 27-gauge instrumentation may be superior to that of early 25-gauge systems, but it is still noticeably more flexible than that of newer 25-gauge instrumentation. This flexibility may present a learning curve for surgeons accustomed to using the shaft of the cutter to translate or tilt the eye, and it may present a challenge in addressing very anterior pathology. On the other hand, the smaller tip size may be beneficial during dissection of membranes, allowing the cutter to act as a membrane pick or to take on characteristics of a malleable soft tip.1 One group has reported that it is possible to peel epiretinal membranes (ERMs) using a 27-gauge cutter without forceps due to the smaller port opening and low sphere of influence (high suction at the ostium of the cutter that rapidly decreases).15,16
Additionally, the tips of 27-gauge forceps are smaller than those of 23- and 25-gauge instruments, which actually have the same size tips despite the difference in gauge. This has led some surgeons to comment that internal limiting membrane (ILM) peeling with 27-gauge forceps has a tendency to lead to more shredding of tissue compared with 23- and 25-gauge forceps tips.
BEST PAIRINGS FOR 27-GAUGE
An increasing number of studies suggests that even the most complex cases can be performed with 27-gauge platforms.4,6,14,17,18 But which cases are ideal for these small-gauge platforms?
Anecdotal reports indicate that there is great value in the use of 27-gauge vitrectomy in eyes that have previously undergone vitrectomy, as the speed of core vitrectomy and the removal of peripheral vitreous is not a factor. Furthermore, the smaller incisions may produce less conjunctival scarring, resulting in decreased postoperative inflammation, and they may seal more frequently than larger-gauge incisions, obviating the need for suturing.
Secondary IOL Fixation
In the fixation of a secondary intraocular lens (IOL) with PTFE Gore-Tex suture, 27-gauge surgery may result in less postoperative hypotony than 23- or 25-gauge vitrectomy, and there may be a decreased risk of inadvertently damaging the PTFE suture if a sclerotomy must be closed because of leakage (Video 1).19 Direct fixation of a three-piece IOL haptic to the sclera may also benefit from the smaller scleral tunnels created with 27-gauge instruments, particularly in patients with thin sclera such as those with pathologic myopia or Marfan syndrome.20
Macular Hole Repair
Although removal of the vitreous takes longer with 27-gauge surgery, the benefits of a sutureless, nonleaking incision may allow a more consistent, complete gas fill and may potentially decrease the need for facedown positioning. Future clinical studies are needed to further investigate the potential benefits of 27-gauge surgery in macular hole repair.
Watch it Now
Video 3. In-Office Air-Fluid Exchange
In this video, Calvin E. Mein, MD, inserts a 25-gauge nonvalved trocar and then uses a bent 30-gauge needle to inject air into the eye of a patient with diabetic vitreous hemorrhage following vitrectomy.
In ocular oncology, molecular prognostication in uveal melanoma is increasingly popular and considered by some to be standard of care.21-23 Studies have indicated that the 27-gauge cutter can be used in a two-port or three-port vitrectomy to obtain tissue samples in uveal melanomas even those less than 2 mm in height.24
For segmenting and delaminating tightly adherent fibrovascular membranes, the smaller sized 27-gauge cutter may be advantageous. Several groups have now reported on the use of hybrid vitrectomy using mixed gauges in one surgical episode for diabetic tractional detachments and retinopathy of prematurity.18,25,26 The use of 23- or 25-gauge vitrectomy packs will still allow the introduction of a 27-gauge cutter for the benefit of its maneuverability and unique fluidics without compromising the use of other instrumentation, such as curved scissors or forceps that are not available in 27 gauge. With the Constellation Vision System, a 27-gauge cutter may be opened by itself in addition to the standard 23- or 25-gauge vitrectomy pack and then used as the primary vitreous cutter through the 23- or 25-gauge cannula. A more cost-effective option is to open a 27-gauge pack and also use standalone 23- or 25-gauge cannulas. Dutch Ophthalmic USA offers the option to produce custom vitrectomy packs that contain a 23-gauge infusion cannula with the other cannulas and cutter of smaller gauge.
The following example illustrates an ideal case for 27-gauge PPV.
A 48-year-old man who had previously undergone scleral buckle band, vitrectomy, membrane peeling, and silicone oil tamponade for a rhegmatogenous retinal detachment with PVR presented with progressively decreasing vision (BCVA 20/100) and metamorphopsia in the right eye. Spectral-domain OCT revealed a dense ERM with distortion of the foveal contour.
Instrumentation for Pediatric Vitrectomy
By Aaron Nagiel, MD, PhD
Vitreoretinal surgery in pediatric patients has its own set of considerations that play into choice of instrumentation. First, eyes in this patient population are smaller, and the width of the pars plana is decreased to varying degrees. This means the lens occupies a greater fraction of the vitreous cavity, and the vitrectomy ports are closer to the lens. Second, the vitreous tends to be formed and more adherent to the retina. Third, much of the pathology in pediatric eyes is located anteriorly.1
Specialized instruments have been developed to address some of these issues. Several surgical companies offer short versions of their vitrectomy packs, which include smaller light pipes, cutters, trocars, and cannulas. Theoretically, with shorter cannulas there should be a diminished risk of touching the lens and increased access to the anterior vitreous.
There has also been an effort to develop small-gauge vitrectomy systems for pediatric patients. Alcon offers 25+ Short products, including a 25+ Short UltraVit Vitrectomy Probe and a 25+ Short Endoilluminator. Dutch Ophthalmic USA is developing a 27-gauge short platform that should be commercially available soon.
Because instrument rigidity is beneficial when dealing with formed pediatric vitreous, it remains to be seen how useful small-gauge instruments will be in this setting. Also, sclerotomies performed in young children should be sutured closed, so the benefits of self-sealing wounds may not be realized in the pediatric population.2
The use of endoscopy has been championed by some pediatric retina surgeons3 because the probes coaxial light source provides better illumination of the vitreous and because it enables improved access to anterior structures that are difficult to visualize with a top-down system. Most surgeons use a 20-gauge straight probe (Endo Optiks), but smaller-gauge versions are in development. Alcon is testing an endoscopic system that will work with the NGenuity 3D Visualization System that the company is developing in collaboration with TrueVision 3D Surgical.
We are in a favorable environment for pediatric vitreous surgery, with an expanding surgical toolset that is customized to the specific needs of pediatric vitreoretinal pathology. Future developments such as high-resolution, small-gauge endoscopic platforms could have the potential to further revolutionize the field.
1. Klufas MA, Patel SN, Chan RV. Surgical management of retinopathy of prematurity. Dev Ophthalmol. 2014;54:223-233.
2. Gonzales CR, Singh S, Schwartz SD. 25-gauge vitrectomy for paediatric vitreoretinal conditions. Br J Ophthalmol. 2009;93(6):787-790.
3. Wong SC, Lee TC, Heier JS, Ho AC. Endoscopic vitrectomy. Curr Opin Ophthalmol. 2014;25(3):195-206.
Aaron Nagiel, MD, PhD
• second-year vitreoretinal fellow at the Jules Stein Eye Institute in Los Angeles, Calif.
• financial interest: none acknowledged
PPV with membrane peel was performed with 27-gauge instrumentation to take advantage of the small incision size. (There was no need to remove vitreous gel because the patient had already undergone vitrectomy.) Three 27-gauge trocar-cannulas were placed in an oblique, beveled fashion, and ILM forceps were used to remove the macular pucker. A partial air-fluid exchange was performed at the conclusion of the case, and the sclerotomies were found to be airtight. The total time from placement of the three ports to removal of the operative drape was less than 6 minutes (Video 2). The patient noted improvement of visual acuity to 20/70 on the first postoperative day despite the partial air fill, and he reported minimal discomfort compared with his prior procedures.
This case exemplifies a remarkably efficient scenario for 27-gauge vitrectomy. In fact, with careful patient selection, in-office vitrectomy procedures with 27-gauge instrumentation may be part of the future. Surgeons have used 25-gauge instrumentation for in-office air-fluid exchange in cases of persistent vitreous hemorrhage after diabetic vitrectomy (Video 3) or vitreous tap-and-inject procedures in endophthalmitis.27 Given the smaller incision size and lower likelihood of wound leak, 27-gauge instrumentation may offer greater advantages for these types of office-based intraocular procedures.
Since the initial development of PPV, instrumentation has progressively become smaller, and 27-gauge instrumentation is now the smallest commercially available for vitreoretinal procedures. The use of 27-gauge instrumentation has been reported for even the most complex vitreoretinal surgical procedures. However, disadvantages of this smaller instrumentation, including increased time to remove vitreous gel, are still not completely overcome by ever-increasing cut rates and higher aspiration. Newer vitrectomy platforms that include an ultrasonic cutter may mitigate these fluidics shortcomings.
Similar to the evolution of 25-gauge vitrectomy, it is likely that further enhancements in 27-gauge instrument design will be . In particular, improving instrument stiffness through a combination of novel designs and materials will be necessary to promote greater interest in 27-gauge surgery. Additional enhancements to cutter designs, with faster cut speeds and increased aspiration, will likely improve efficiency in 27-gauge vitrectomy.
1. Osawa S, Oshima Y. 27-gauge vitrectomy. Dev Ophthalmol. 2014;54:54-62.
2. Oshima Y, Wakabayashi T, Sato T, et al. A 27-gauge instrument system for transconjunctival sutureless microincision vitrectomy surgery. Ophthalmology. 2010;117(1):93-102.
3. Khan MA, Shahlaee A, Toussaint B, et al. Outcomes of 27 gauge microincision vitretctomy surgery for posterior segment disease. Am J Ophthalmol. 2016;161:36-43.
4. Romano MR, Cennamo G, Ferrara M, et al. Twenty-seven-gauge versus 25-gauge vitrectomy for primary rhegmatogenous retinal detachment [published online ahead of print July 26, 2016]. Retina.
5. Rizzo S, Barca F, Caporossi T, Mariotti C. Twenty-seven-gauge vitrectomy for various vitreoretinal diseases. Retina. 2015;35(6):1273-1278.
6. Toygar O, Mi CW, Miller DM, Riemann CD. Outcomes of transconjunctival sutureless 27-gauge vitrectomy with silicone oil infusion. Graefes Arch Clin Exp Ophthalmol. 2016;254(11):2111-2118.
7. Fujii GY, De Juan E Jr, Humayun MS, et al. A new 25-gauge instrument system for transconjunctival sutureless vitrectomy surgery. Ophthalmology. 2002;109(10);1807-1812.
8. Eckardt C. Transconjunctival sutureless 23-gauge vitrectomy. Retina. 2005;25(2):208-211.
9. Cohen MN, Houston SK 3rd, Roberts AL, et al. Analysis of pars plana vitrectomy incisions using live bacteria [published online ahead of print September 23, 2016]. Retina.
10. Mitsui K, Kogo J, Takeda H, et al. Comparative study of 27-gauge vs 25-gauge vitrectomy for epiretinal membrane. Eye (Lond). 2016;30(4):538-544.
11. Pavlidis M. Two-dimensional cutting (TDC) vitrectome: in vitro flow assessment and prospective clinical study evaluating core vitrectomy efficiency versus standard vitrectome. J Ophthalmol. 2016;2016:3849316.
12. Steel DH, Charles S. Vitrectomy fluidics. Ophthalmologica. 2011;226 Suppl 1:27-35.
13. Abulon DJ, Buboltz DC. Porcine vitreous flow behavior during high-speed vitrectomy up to 7500 cuts per minute. Transl Vis Sci Technol. 2016;5(1):7.
14. Watanabe A, Tsuzuki A, Arai K, et al. Treatment of dropped nucleus with a 27-gauge twin duty cycle vitreous cutter. Case Rep Ophthalmol. 2016;7(1):44-48.
15. Coppola M, La Spina C, Querques G, Bandello F. Epiretinal membrane peeling without forceps: an alternative use of the 27-gauge vitrectomy probe. Retina. 2016;36(10);2029-2030.
16. Dugel PU, Abulon DJ, Dimalanta R. Comparison of attraction capabilities associated with high-speed, dual-pneumatic vitrectomy probes. Retina. 2015;35(5):915-920.
17. Takkar B, Azad S. Outcomes of 27 gauge microincision vitrectomy surgery for posterior segment disease. Am J Ophthalmol. 2016;164:145.
18. Oellers P, Mahoud TH. Surgery for proliferative diabetic retinopathy: new tips and tricks. J Ophthalmol Vis Res. 2016;11(1):93-99.
19. Khan MA, Rahimy E, Gupta OP, Hsu J. Combined 27-gauge pars plana vitrectomy and scleral fixation of an Akreos AO60 intraocular lens using Gore-Tex suture. Retina. 2016;36(8):1602-1604.
20. Todorich B, Thanos A, Woodward MA, Wolfe JD. Sutureless intrascleral fixation of secondary intraocular lens using 27-gauge vitrectomy system. Ophthalmic Surg Lasers Imaging Retina. 2016;47(4)376-379.
21. Singh AD, Medina CA, Singh N, et al. Fine-needle aspiration biopsy of uveal melanoma: outcomes and complications. Br J Ophthalmol. 2016;100(4):456-462.
22. McCannel TA. Fine-needle aspiration biopsy in the management of choroidal melanoma. Curr Opin Ophthalmol. 2013;24(3):262-266.
23. Shields CL, Ganguly A, Materin MA, et al. Chromosome 3 analysis of uveal melanoma using fine-needle aspiration biopsy at the time of plaque radiotherapy in 140 consecutive cases. Trans Am Ophthalmol Soc. 2007;105:43-52.
24. Nagiel A, McCannel CA, Moreno C, McCannel TA. Vitrectomy-assisted biopsy for molecular prognostication of choroidal melanoma 2 mm or less in thickness with a 27-gauge cutter [published online ahead of print October 31, 2016]. Retina.
25. Hubschman JP, Gonzales CR, Bourla DH, et al. Combined 25- and 23-gauge surgery: a new sutureless vitrectomy technique. Ophthalmic Surg Lasers Imaging. 2007;38(4):345-248.
26. Yonekawa Y, Thanos A, Abbey AM, et al. Hybrid 25- and 27-gauge vitrectomy for complex vitreoretinal surgery. Ophthalmic Surg Lasers Imaging Retina. 2016;47(4):352-355.
27. Vahedi S, Adam MK, Dollin M, Maguire JI. 25-gauge trocar cannula for acute endophthalmitis-related in-office vitreous tap and injection: patient comfort and physician ease of use [published online ahead of print July 28, 2016]. Retina.
Jason Hsu, MD
• co-director of retina research and faculty member of the retina service of Wills Eye Hospital; managing partner, Mid Atlantic Retina; and assistant professor of ophthalmology, Thomas Jefferson University, all in Philadelphia, Pa.
• financial interest: none acknowledged
Michael A. Klufas, MD
• faculty member of the retina service of Wills Eye Hospital; vitreoretinal surgeon, Mid Atlantic Retina; retina chief, Eyetube.net; and assistant professor of ophthalmology, Thomas Jefferson University, Philadelphia, Pa
• financial interest: none acknowledged
• @NJRetinaDoc; firstname.lastname@example.org