In 2010, publications confirmed the safety and feasibility of 27-gauge surgery. Since then, more data describing its use – in even the most complex vitreoretinal surgical procedures – has been published. As interest grows, and the noted learning curve becomes less daunting to vitreoretinal surgeons, the makers of the retinal surgery platforms have taken notice and are stepping up to meet the increasing need.
Alcon (Fort Worth, TX, USA) has released the Constellation Vision System; Dutch Ophthalmic Research Center (DORC, Zuidland, Netherlands) has made 27-gauge vitrectomy packs available for the EVA vitrectomy system; and Bausch + Lomb (Rochester, NY, USA) is also developing a 27-gauge platform for its Stellaris PC Vision Enhancement System.
So, what’s the big deal with 27-gauge, and why would we make the switch?
Well, one of the major criticisms of 23- or 25-gauge vitrectomy is that the resulting sclerotomies do not seal completely, potentially leading to an increased risk of hypotony, choroidal detachment, or endophthalmitis. By decreasing the gauge size, the risk of these complications can also possibly be lowered.
Reduced risk of complications is a definite benefit, but smaller instruments also mean removal of the vitreous will take longer. However, even though it may take more time, these 27-gauge cutters have shown that they can remove half of the nucleus from the posterior segment, eliminating the need for a fragmatome.
The learning curve that most vitreoretinal surgeons refer to is related to the rigidity, or lack thereof, with the 27-gauge instrumentation. The increased flexibility of the 27-gauge over the 25-gauge instrument may present some challenges initially, but surgeons have reported that the smaller tip is more beneficial for membrane dissection, even allowing epiretinal membranes to be peeled without forceps.
So, what technology is currently available?
Alcon’s Constellation Vision System continues to deliver advanced technologies and the latest tools to meet the needs of vitreoretinal surgeons. The company’s 27+ Vitrectomy Packs and Instrumentation for use with the Constellation includes a full range of instruments designed for complex, micro-incision vitrectomy procedures. Alcon has focused on providing surgeons with exceptional access to the small tissue areas of the eye, while also providing a probe stiffness experience similar to the 25+, by using a proximal sleeve that stabilizes the instrument at the trocar interface, allowing for better control during procedures.
Alcon has also addressed a way to reduce traction that may lead to iatrogenic tears and postoperative complications, and delivers high speed 7500 cpm dual pneumatic drive technology with 27+, consistent with their 20, 23, and 25+ series. This dual pneumatic vitreous cutter, relies on independent airflow to drive the closing and opening of the cutter, while the port location has been optimized by placing it closer to the tip.
Surgeons using Alcon’s Constellation Vision System also have the freedom to modify duty cycle to control flow independent of vacuum and cut rate. They have the ability to select from three different duty cycle options at any given cut rate, Port Biased Open, 50/50, or Port Biased Closed. The Constellation also continuously monitors infusion pressure through the IOP compensation feature, resulting in better control and more stable IOP.
Finally, the Constellation delivers state-of-the-art illumination technology for visualizing ocular tissues, including the ENGAUGE Radio Frequency Identification Device Technology (RFID). This recognizes light probe gauge size and automatically adjusts light intensity. In addition, the Xenon Illuminator is designed to provide long-lasting high brightness illumination.
EVATM, from Dutch Ophthalmic Research Center (DORC) is another retinal surgery system, (actually a cataract and vitrectomy system), that has stepped up to meet the need for 27-gauge surgery. DORC recognizes that smaller instruments can enhance wound construction, reducing the need to suture, making vitreoretinal surgery less invasive than ever before.
The challenge of flexibility with the 27-gauge instrumentation was addressed by the rigid shaft design to optimize performance during core and peripheral vitrectomy. EVA includes a LEDStar illumination system, which is a three port light emitting diode (LED) illumination and has the added benefit of constant lumen output. This means that there is no degradation of light output over the +10,000 hour life of the LED. Unique to EVA is the TDC, a two-dimensional cutter which delivers a cut speed of up to 8000 cpm and is designed to facilitate cutting tissue on the return of each stroke of the vitrectome, effectively doubling the cut speed to up to 16,000 cpm.
The Stellaris PC Vision Enhancement System from Bausch + Lomb accommodates instrumentation ranging from 23- to 25-gauge, with a 27-gauge in the pipeline.
Also, of note, is the VersaVIT 2.0 vitrectomy system from Synergetics (O’Fallon, MO, USA), which is carving out its place as a small, portable vitrectomy platform. This “size of a suitcase” vitrectomy platform has a maximum cute rate of 6000 cpm and will soon have VersaVIT procedures packs for 20- and 27-gauge available.
So, is smaller better? Small gauge vitrectomy, is intended to be transconjunctival, self-sealing, and sutureless. It has the potential to reduce complications and to be better suited to smaller, pediatric eyes. All great benefits, but the confines of instrument diameter and lumen may be limiting on instrument flexibility, efficiency, and performance – thus, making it best suited for specific cases.
As we know, instrumentation for vitreoretinal surgery is continuously evolving, and companies are eager to address challenges to meet the needs of surgeons. So the better question might be: How small can we go?
References:
Lin X, Apple D, Hu J, Tewari A. Advancements of vitreoretinal surgical machines. Curr Opin Ophthalmol. 2017;28(3):242-245.
Mohamed S, Claes C, Tsang CW. Review of Small Gauge Vitrectomy: Progress and Innovations. J Ophthalmol. 2017;2017:6285869
