Most vitreoretinal surgeons today routinely use 25- or 23-gauge vitrectomy systems, but when the conversation turns toward the next stage in the small-gauge evolution — 27-gauge vitrectomy — concerns about flexible instruments, slow procedures, and inadequate illumination tend to resurface.
In response to these concerns and with an eye toward future advancements in vitreoretinal surgery, Dutch Ophthalmic Research Center (DORC) incorporated innovative new technology into its Enhancing Visual Acuity (EVA) surgical system, most notably a novel 2-dimensional cutting (TDC) vitrectomy probe, a VacuFlow valve timing intelligence (VTi) pump system, a high-flow infusion cannula, a high-powered LED light source, and several new instruments specifically designed for 27-gauge surgery.
While the EVA platform is best assessed in its entirety as a fully integrated surgical system, we asked early adopters to describe the advantages of the individual components, starting with the TDC vitrectomy probe.
A First: 2-dimensional Cutting
Designed and developed by DORC in collaboration with Mitrofanis Pavlidis, MD, Cologne, Germany, the TDC vitrectomy probe was engineered specifically for use with the EVA surgical system. Unlike conventional cutters, the TDC probe cuts both forward and backward (Figure 1), effectively doubling the maximum cut rate to 16,000 cuts per minute (cpm).
While other systems allow surgeons to adjust duty cycle for port-biased open (core vitrectomy mode) and port-biased closed positions (proportional vacuum/shave mode), the EVA TDC vitrectomy system produces a constant duty cycle of 92% biased-open position and maintains aspiration even when the blade is in the “closed” position. In other words, the port is open 92% to 100% of the time, creating constant aspiration flow independent of cutting speed (Figure 2). These functions, along with other features of the EVA system, combine to create faster, more efficient surgeries.
In a comparative case series reported by Pavlidis in 2016, the mean duration of core vitrectomy procedures using 25-gauge and 27-gauge TDC vitrectomy probes was statistically significantly shorter than the mean duration for core vitrectomies performed with standard single-cut probes of the same gauge.1 Procedures performed using a 27-gauge TDC probe were 34% shorter (−83.0 seconds) than those performed using a standard 27-gauge single-cut probe.
Similar results were reported for 25-gauge vitrectomies: procedures performed using a TDC vitrectomy probe were 50% shorter (−74.39 seconds) than those performed with a standard probe.
According to the study’s author, these findings suggest that the TDC vitrectomy probe provides greater operating efficiency than conventional instrumentation during sutureless, small-gauge vitrectomy. Surgeons who are using this technology concur.
TDC’s Impact on 27-gauge Surgery
Speed, efficiency, and safety are most often cited by surgeons as the most important features of any vitrectomy system, and advancements in these areas have made the transition to 27-gauge not only feasible but preferable for many surgeons.
“The TDC vitrectomy probe really shines in 27-gauge surgery,” says Asheesh Tewari, MD, Ann Arbor, Mich. “The main sticking point for 27-gauge surgery before the introduction of 2-dimensional cutting was the time required to complete the vitrectomy. With a cutter capable of operating at 16,000 cpm and the advanced fluidics of the EVA system, that is no longer a concern.”
Dr. Tewari’s transition to 27-gauge surgery was driven mainly by its utility for diabetic cases.
“Surgical repair of tractional retinal detachment is a fairly delicate procedure, requiring us to navigate through tight spaces and around blood vessels to remove scar tissue from the retinal surface,” he says. “If we get too close to blood vessels, they bleed. If we get too close to the retina, we can cut it, which changes the whole dynamic of the case.
“Traditionally, when using 23-gauge instrumentation, membrane dissections would be time-consuming,” Dr. Tewari says. “I would often have to use several different instruments to enter into the various surgical planes. Twenty-seven gauge has changed that quite a bit, because the cutter port is so small that I can easily access those planes with the vitrectomy cutter alone.”
Dr. Tewari also appreciates that the TDC probe acts as a multifunctional device, often replacing scissors and sometimes forceps, minimizing the number of instruments going in and out of the eye. “In my opinion, 27-gauge instrumentation has a distinct advantage over traditional larger-gauge instrumentation, which is why I am transitioning to 27-gauge in the vast majority of my diabetic cases,” Dr. Tewari says.
Using the 27-gauge cutter as a multi-functional tool is also high on the list of benefits related by Gaurav K. Shah, MD, St. Louis. “Being able to use the cutter to peel membrane, to get into tight spaces, and to have better control in the eye saves time in the OR,” he says. “In addition, the smaller the cutter, the less chance of iatrogenic complications caused by engaging tissues that we do not want to engage.”
Twenty-seven gauge has become Dr. Shah’s predominant gauge for most if not all of his cases. He attributes his nearly complete conversion to 27-gauge to the TDC vitrectomy probe.
“Small-gauge instrumentation — whether you use 23-, 25-, or 27-gauge — has made a big impact on what we do,” Dr. Shah says. “For me, 27-gauge with the TDC vitrectomy probe has made the biggest difference, particularly compared with 27-gauge surgery with a non-TDC probe. It would be akin to eating with a fork with three tines versus a fork with one tine. Both are forks, but using the former is faster and more efficient. In my opinion, the TDC vitrectomy probe is one of the best improvements in terms of making 27-gauge viable for most of my cases.
Brian C. Joondeph, MD, Denver, who uses predominantly 23-gauge instrumentation, appreciates the versatility of the 27-gauge cutter for certain situations. “It is small enough that I can get underneath membranes and use the cutter to engage, peel, and cut membranes that I might not be able to do with a 23-gauge cutter, particularly in diabetic patients,” he says. “For me, that is a big advantage.”
The 27-gauge instrument is also ideal for quick cases, such as vitreous hemorrhage and floaters, that require little to no retinal work, according to Dr. Joondeph. “I can get into the eye via a small incision, get my work done, and get out, and the eyes are white, quiet, and comfortable the next day,” he says.
According to Colin A. McCannel, MD, Los Angeles, the unique design of the TDC vitrectomy probe contributes not only to the speed with which procedures can be completed, but also to overall safety.
“Because the port of the TDC vitrectome is not completely occluded, we are achieving higher flow rates for quicker vitreous removal and fluid aspiration,” Dr. McCannel says. “In addition, because the blade is cutting in both directions, we are doubling the cut rate, which minimizes any traction that either flow control or vacuum control might have on the vitreous. The EVA can be turned down to 8,000 cpm, but it works perfectly well at the highest cut rate while minimizing vitreous traction. In addition, frequently disconnecting the aspirated vitreous from the vitreous that is still attached to the retina at a clip of 16,000 times a minute gives us another measure of safety in addition to the improved fluidics.”
Minimizing Discomfort
“One of the reasons why I have embraced 27-gauge vitrectomy technology with open arms is because my patients remark on post-op day 1 that they do not feel like they had eye surgery at all,” says Colin A. McCannel, MD, Los Angeles. “They have zero discomfort, and instances of borderline low pressures are extremely rare. The tradeoff in the OR of longer vitreous removal times — which are really no longer with 27-gauge TDC than with 25-gauge non-TDC instrumentation — are really obviated by the comfort advantage. It has been a wonderful tradeoff. Patients very much appreciate it.”
Gaurav K. Shah, MD, St. Louis, agrees that minimally invasive vitreoretinal surgery with small-gauge instrumentation has had a positive impact on patients’ comfort, with shorter procedure times, smaller self-sealing wounds, less postoperative inflammation, and quicker recoveries.
“In retina, we have paid little attention to comfort when it comes to surgery, assuming that retina surgery hurts,” Dr. Shah says. “Well, no. Surgery should not hurt, unless it has to. While we are focused on fixing the anatomy, we need to do so in the least invasive way possible. I have learned that pain is minimal to nonexistent when patients have had 27-gauge vitrectomy.”
For the same reasons laparoscopic surgeries are preferred over open surgeries in other areas of medicine, so too are minimally invasive retina surgeries, Dr. Shah says.
“With minimally invasive surgeries, patients are more comfortable, they recover faster, and they have better outcomes,” Dr. Shah says. “Can every case be done that way? Of course not. But if we use the skills that we have, augment them, and have an open mind, we can do a very good job for our patients in the least invasive fashion.”
A Simple Concept
“This is one of those times when you say to yourself, ‘Why didn’t I think of that?’ Dr. Tewari says. “Two-dimensional cutting is such a simple concept. Put a blade on both sides of the cutter so that as it moves forward and backward, it is always cutting vitreous. If it is always cutting vitreous, the port is never really closed, and if the port is never closed, you are still aspirating fluid. This cutter really changes the whole game of fluidics.”
In addition, Dr. Joondeph notes, because the cutter port is always open, fluid is constantly flowing, and surges do not occur. “When I began using the 23-gauge TDC vitrectomy probe, I was amazed how quickly I could complete a vitrectomy,” he says. “All of a sudden it was done. The time it usually took just to remove vitreous from the eye before doing anything else was much faster. That is a big plus of the TDC probe.”
According to Dr. Shah, early concerns that small-gauge vitrectomy probes were too small and too flexible to have value have gone by the wayside.
“The maneuverability and the safety of the TDC probe now works to its advantage,” he says. “For me, 23-gauge is still going to be useful for certain cases, such as foreign body cases and very anterior pathology, but even those cases I have tackled with 27-gauge because it works. Certainly, a bit more initial skill is involved, but we teach it, and our fellows are able to do it. Sometimes, people are too quick to give up on new technology just because it ‘doesn’t feel like what I am using.’ Well, it’s not supposed to feel like what they were using. This is something new.” ■
References
- Pavlidis M. Two-dimensional cutting (TDC) vitrectome: in vitro flow assessment ad prospective clinical study evaluating core vitrectomy efficiency versus standard vitrectome. J Ophthalmol. E-pub April 12, 2016.
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