Vitrectomy Machines, Fluidics, and Small-Gauge Systems Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 38–44 (DOI: 10.1159/000360447)

23-Gauge Vitrectomy Peter Stalmans  Department of Ophthalmology, University Hospitals Leuven, Leuven, Belgium

Smaller-gauge surgery enables greater precision and offers advantages in decreased surgical time, less tissue manipulation, reduced inflammation, postoperative pain, and more rapid visual recovery. While smaller instruments create smaller incisions that violate the eye less, it can be more difficult to fit the instruments required to accomplish tasks through the port. For many surgeons, 23-gauge techniques and instruments offer an ideal compromise between the cumbersome, suture-requiring 20-gauge procedures and the smaller, but more limited, 25- and 27-gauge surgeries. © 2014 S. Karger AG, Basel

Many specialists choose sutureless, small-incision surgery to ensure quieter eyes in the vitreoretinal patient. The biggest advantage over largergauge procedures is reduced postoperative inflammation at the sclerotomy site, enabling speedier recovery and improving postoperative patient morbidity. In addition, operating time is reduced, which cuts costs, and the small incisions are especially appropriate for working on children’s eyes. 23-gauge surgery was developed to offer an alternative to 20-gauge surgery and solve

many of the early issues of too much instrument flexibility and limited light options associated with smaller 25-gauge techniques. It has become the approach-of-choice for most vitreoretinal procedures today. Development of 23-Gauge Vitrectomy

17-gauge pars plana vitrectomy was first introduced more than 40 years ago. The use of 20-gauge instrumentation became standard in the 1980s and 1990s. Sutureless procedures for 20-gauge instruments were first introduced in 1996. At the time, introducing instruments through a self-sealing, scleral-tunnel sclerotomy was a novel approach that presented many challenges. Complications such as wound leakage, vitreous incarceration, and retinal tears were common hazards, and conjunctival dissection and suturing were often required. The introduction of small trocar-cannulas paved the way for greater advances in vitreoretinal surgery. 25-gauge instruments were developed in 1990, but 25-gauge transconjunctival sutureless vitrectomy was not introduced until 2002. Sharing characteristics of both its forerunners, 23-gauge

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Abstract

Uses of 23-Gauge Vitrectomy

23-gauge surgery was originally used for macular procedures, but with advances in instrumentation and techniques, it has become a favored approach for most vitreoretinal procedures.

23-gauge surgery is possible in all cases except removal of a foreign body, where a larger sclerotomy is needed, or removal of subretinal membrane, which requires angled instruments. Advantages

23-gauge vitrectomy has many advantages over 25- and 27-gauge vitrectomy, mainly due to the larger diameter and greater rigidity of the instruments. One major advantage is that the plugs for the 23-gauge instrument allow the injection and extraction of silicone oil. When a narrow-wall polyamide 23-gauge cannula is fitted on the injection syringe, a complete 1,000-cSt oil fill can be obtained in less than 1 min. Since the sclerotomies are made with a myringovitreoretinal (MVR) blade in 23-gauge surgery, a slit-like incision is made obliquely in the sclera (although a 25-gauge MVR blade is also now available); these incisions are always self-sealing and postoperative hypotony is not an issue. Compared to 20-gauge vitrectomy, the 23-gauge procedure also has many advantages. Since no conjunctival peritomy is required, less discomfort and postoperative inflammation is noted in patients undergoing 23-gauge surgery. Moreover, the presence of self-closing valves over the instrument canulas prevent fluid leakage from the eye during surgery, stabilizing the intra-ocular pressure and reducing the fluid current in the vitreous cavity (fig. 1). Sutureless Surgery Smaller-gauge surgery, including 23-gauge procedures, can be performed without sutures because the incisions made are, of course, smaller and generally self-healing. Sutures can leave inflammatory nodules on the surface of the eye that can take weeks, or even longer, to resorb. Large incisions and sutures can leave patients with red eyes after surgery and can warp the eye’s surface. Patients undergoing sutureless surgery can expect less postoperative astigmatism since sutur-

23-Gauge Vitrectomy Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 38–44 (DOI: 10.1159/000360447)

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vitrectomy soon followed in 2005. It was smaller than 20-gauge vitrectomy, but more rigid than 25-gauge vitrectomy, making procedures such as endolaser and removal of the peripheral vitreous gel easier for most surgeons. Although the use of 25-gauge instruments reduced surgery time, as suturing of the sclerotomies was omitted, and improved postoperative recovery, the narrow inner lumen of the instrument slowed down the removal of the vitreous. Moreover, the smaller gauge initially posed some problems for surgeons because of the increased flexibility of the instruments, which limited what procedures could be performed. In addition, the standard light source for 25-gauge surgery was initially less bright because fewer lumens could be transmitted through the smaller-gauge fiber optic light pipe. 23-gauge instruments and techniques were developed in response to the concerns over decreased rigidity and light in 25-gauge surgery. They provided more rigid instrumentation with better light transmission, allowing greater rotation of the eye, as well as a larger inner lumen, whereby the ability to perform a more complete vitrectomy was enhanced. Subsequent technological advances have lessened the impact of the initial issues and have made it possible to expand the scope of smaller-gauge surgery. Because 23-gauge surgery has been performed since 2005, it has been possible to scientifically evaluate its benefits and limitations. Large-scale studies of postoperative comfort and reduced clinical risks in patients who have undergone vitrectomy using 23-gauge instruments and procedures have been undertaken and compared with surgical procedures using other gauges. The results have shown definitive benefits.

Fig. 1. Peroperative view of 23-gauge vitrectomy. All three valved cannulas are inserted in the pars plana. The infusion line is inserted into the lower temporal cannula. Since three identical cannulas are used, the surgeon can freely switch over the infusion line into another cannula if desired. The valves prevent leakage from the cannulas when no instruments are inserted.

Increased Procedure Speed Savings in procedure time can be achieved with 23-gauge surgery. As well as saving time in suturing, the smaller instrumentation simply enables quicker surgery. New surgical platforms, such as the Enhanced Visual Acuity System (EVA) from the Dutch Ophthalmic Research

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Centre (DORC) offer improved fluidic control that also contributes to enhanced procedure speed, as well as safety. In addition to improved fluidics, the system offers better control of duty cycles and cutting rates. High-speed cutting is an important option in working with smaller-gauge instrumentation, not only because it is faster, but also because it minimizes pulsatile vitreoretinal traction. Better Efficiency Using 23-gauge instruments, suturing the infusion and sclerotomies is no longer necessary, which not only shortens surgery time, but requires less than half as many instruments. This means that a smaller number of instruments need cleaning after surgery, saving even more time. Reduced Risks One of the most serious complications from vitrectomy is endophthalmitis, a serious ocular condition which can result in irreversible loss of vision. Incidence of this condition is of particular concern when evaluating any new surgical technique. Early studies indicated that incidences of endophthalmitis in 25-gauge surgery were significantly higher than 20-gauge procedures. Subsequent studies have shown that a sutureless trans-

Stalmans Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 38–44 (DOI: 10.1159/000360447)

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ing of the sclerotomies is typically not required, and they can expect reduced conjunctival trauma and inflammatory response of the eye. Sutureless surgery also reduces operation time because opening and closing the sclerotomies and conjunctiva are not required. Sclerotomies with a width of 0.72 mm are needed for 23-gauge instruments. While this would normally require closure with a suture, it can be avoided by performing a tunnel incision that achieves self-healing. Instead of a usual perpendicular incision through the sclera, as in 25-gauge surgery, a tunnel-like tangential incision is made at a 30–40° angle. Suture closure is not required because the wound borders close the incision in a valve-like manner through intraocular pressure. The transconjunctival sclera at tunnel incision created for 23-gauge instruments guarantees an almost 100% rapid self-sealing closure rate.

a

b

Fig. 2. Comparison of different gauges. a 20-, 23-, 25- and 27-gauge instruments (from left to right). The 23-gauge vitrectome offers the optimal compromise between rigidity and flow diameter. b 20-, 23-, 25- and 27-gauge endgripping forceps. The tip of the 23-gauge forceps has a similar shape as the 20-gauge version, but offers markedly more grip than the 25- or 27-gauge version.

Enhanced Postoperative Comfort Postoperative pain, eye discomfort, and necessary sick leave are inevitable consequences of vitrectomy. However, studies have shown that 23-gauge pars plana vitrectomy causes significantly less postoperative pain and discomfort compared to 20-gauge pars plana vitrectomy [2]. Following 20-gauge surgery, the patients studied had a significantly increased risk of sleeping less during the first postoperative night and week, waking up due to pain during the first postoperative night and week, taking pain medication during the first postoperative night and week, and using a postoperative ointment. They also experienced a longer period of postoperative discomfort and red-

dish eyes. Larger incisions, longer procedures, suturing, and exposure of the bare sclera in 20-gauge surgery creates more postoperative discomfort and inflammation. 23-gauge transconjunctival sutureless techniques cause no surgical trauma to the conjunctiva, require no sclera suturing, and cause less postoperative discomfort. Compared to 20-gauge vitrectomy, both 23- and 25-gauge vitrectomy share the same advantages: little or no trauma to the conjunctiva, no suture-related inflammation or discomfort, and no postoperative astigmatism. In addition, the transconjunctival technique does not interfere with present filtration blebs or future filtration surgery. The major advantage of 23-gauge vitrectomy over 25-gauge vitrectomy is that it can be successfully performed in most complicated cases. Moreover, silicone oil can be used easily using a 23-gauge system, which is difficult in the 25-gauge variety, mainly when 5,000 cSt oil are used. The duration of sick leave in patients who had underwent 20-gauge surgery compared to 23-gauge procedures showed no significant difference [2], possibly due to the use of a fibrin sealant in conjunctival closure, which is known to reduce postoperative pain and discomfort. Shorter Patient Hospitalization Due to less postoperative pain and discomfort, patients undergoing 23-gauge procedures can

23-Gauge Vitrectomy Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 38–44 (DOI: 10.1159/000360447)

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conjunctival approach using a 23-gauge procedure has a reduced risk [1] and can overcome some of the shortcomings of 25-gauge surgery with the benefits of a larger caliber, more rigid instruments, and more efficient cutters, while at the same time retaining many of the advantages of 25-gauge vitrectomy (fig. 2). In addition, passive backflush instruments can be used in a 23-gauge system, while active aspiration is required in 25- and 27-gauge surgery. Passive aspiration is safer compared to active aspiration since no collapse of the eye can occur – a risk with active aspiration, particularly when aspiration under air infusion is performed.

Better for Children Smaller instruments and incisions are particularly well suited for surgery in the smaller eyes of pediatric patients, such as in cases of persistent fetal vasculature, retinopathy of prematurity, uveitis, and some instances of uncomplicated tractional or rhegmatogenous retinal detachments. Sometimes it can be necessary to use 20-gauge surgery, such as for stage 5 retinopathy of prematurity, but in most cases it makes sense to use smaller-gauge surgery in children. In really small eyes, however, the trocar can be problematic with small-gauge procedures. A 23-gauge incision can be made and the 23-gauge instrument can be used without a trocar. Using sutures after the procedure in this case, a small section of the conjunctiva can be taken down to better visualize the wound and minimize the risk of hypotony. Limitations

Costs The main disadvantage of 23-gauge vitrectomy is higher cost. However, requiring no sutures and fewer instruments reduces material costs, and the shorter surgery time and less postoperative treatment needed offer additional significant savings. Training Getting fully acquainted with performing 23-gauge surgery requires moderate adjustment, mostly with regard to the procedures. However, 23-gauge instruments nowadays are similar to 20-gauge ones in rigidity, lighting, flow, and aspiration of the vitreous cutter.

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Flow Control Smaller-gauge instruments enable greater precision in procedures and has certain advantages; however, working with smaller gauges requires a higher level of understanding of flow characteristics because all material must travel through a smaller diameter tube. Higher infusion and aspiration pressures are needed to remove the vitreous when working with 23- (25- and 27-) gauge probes. Advanced platforms offer enhanced flow control, notably EVA, which features a unique flow control system (VacuFlow VTi®) that provides a combined flow and vacuum system, enabling the surgeon to choose between vacuum and flow modes. This system overcomes the limitations of existing Venturi and peristaltic pumps and opens new possibilities in 23-gauge surgery. Clinical Procedures A small number of limitations in terms of the clinical procedures that can be performed exist with 23-gauge procedures. Surgery requiring curved instruments such as tractional diabetic retinal detachments and macular translocations are the only indications for 20-gauge vitrectomy. Complications Wound leakage and endophthalmitis are still, of course, possible complications of 23-gauge surgery; however, appropriate techniques and equipment can minimize complications. Techniques

Techniques to minimize complications in 23-gauge surgery play a significant role in optimizing outcome. Wound Architecture Conjunctival displacement allows the conjunctiva to cover the wound and is an important aspect of wound construction. Additionally, construct-

Stalmans Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 38–44 (DOI: 10.1159/000360447)

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usually be released from hospital after 1 night, providing an ambulant check-up is planned on postoperative day 2 or 3, whereas patients undergoing 20-gauge surgery tend to require 2 nights of hospitalization.

Fluid-Air Exchange Another approach to minimizing postoperative wound leakage and subsequent complications is the use of fluid-air exchange at the end of a vitrectomy. Because of higher surface tension, air is less likely to leak through the incision than fluid. If leakage does occur, however, the sclerotomy site can be closed with a 7-0 or 8-0 Vicryl suture. Antibiotics Injection of postoperative antibiotics reduces the risk of endophthalmitis considering the 100:1 antibiotic concentration gradient between the front and back of the eye. Inject subconjunctival antibiotics under the lower lid in the inferior cul-de-sac, so if there is a subconjunctival hemorrhage, the patient will not see it and the antibiotics cannot reflux into the wounds. High-Speed Cutting This minimizes pulsatile vitreoretinal traction. Instrumentation

Advances in instrumentation for 23-gauge surgery are continually expanding. Today, it is easy to find a wide range of vitreous cutters, chandeliers, curved scissors, microvitreoretinal blades, aspirating picks, and endoscopic laser probes for 23-, 25-, and 27-gauge surgery. This, in turn, has made it possible to expand the indications for these procedures. Twin Duty Cycle Vitrectome A new cutter type will soon be available that is equipped with an opening in the vitrectome blade

(DORC’s twin duty cycle cutter) for use with 23(25- and 27-) gauge instrumentation in DORC’s EVA platform. This feature offers two advantages. First, each time the cutter opens and closes, two cuts are made, which effectively produces cut rates up to 16,000 cuts/min. Secondly, even when the blade is in the closed position, the port is not occluded, which enhances the flow through the system. As a result, even at maximal cut rates and using flows around 4 ml/min, there is almost no buildup of a vacuum in the aspiration line, which provides precision control of the flow in the tubing. With the twin duty cycle cutter, the vitreous is brought into the inner aperture and cut in a forward and backward movement, increasing the amount of vitreous that is cut in a single motion. The aperture in the inner tube results in almost constant aspiration flow into the port. The inner port on the new cutter is larger than previous designs which should enable a larger amount of material to be taken in per cut and increase the speed of surgical procedures. The twin duty cycle vitrectome removes 2–3 times more vitreous than a standard cutter. 23-Gauge Dual Light Probe While many vitreoretinal procedures can be performed using a conventional hand-held light probe for endoillumination, more complicated cases require chandelier illumination. A new 23-gauge dual light probe (DORC) resembles a conventional 23-gauge light probe, with 27-gauge light fiber offering wide-angle viewing and a 23-gauge hand piece. However, the fiber can be moved in and out of its posterior end and features a small adjustable silicone disk which serves as a stopper. For use as a chandelier endoilluminator during vitrectomy, the silicone stopper can be positioned 4 mm from the end of the fiber and the fiber can be inserted into one of the two ports of the trocar-microcannula system with the other port accessible for instrumentation. The change from a hand-held probe to a chandelier takes only a few seconds.

23-Gauge Vitrectomy Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 38–44 (DOI: 10.1159/000360447)

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ing scleral tunnels by an oblique wound is a second critical step. Angling the incision creates a flap, which pressure-closes when the instruments and trocar are pulled out. Angled incisions like these can cut leakage by half.

Developments in the Pipeline

Implications for Industry

While a two-step cannula system with separate MVR knife was previously considered to be the best way of achieving an accurate incision with minimal insertion force, creating a self-healing wound, DORC is developing the new-generation One-Step MVR Cannula System, which has an integrated MVR blade providing all these benefits plus added convenience. The system is available for 23-, 25-, and 27-gauge instrumentation.

23-gauge techniques and instruments are ideal for many surgeons and are likely to lead to rapid further development of new instrumentation and systems that optimize this modality.

References   2 Mentens R, Stalmans P: Comparison of postoperative comfort in 20 gauge versus 23 gauge pars plana vitrectomy. Bull Soc Belge Ophtalmol 2009;311:5–10.

Peter Stalmans, MD, PhD University Hospitals Leuven, Campus Sint-Rafaël, Ophthalmology Kapucijnenvoer 33 BE–3000 Leuven (Belgium) E-Mail [email protected]

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Stalmans Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 38–44 (DOI: 10.1159/000360447)

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  1 Paolini B, Romanelli F, Prigione G, Pertile G: Incidence of endophthalmitis in a large series of 23-gauge and 20-gauge transconjunctival pars plana vitrectomy. Graefes Arch Clin Exp Ophthalamol 2009;247:895–898.

23-gauge vitrectomy.

Smaller-gauge surgery enables greater precision and offers advantages in decreased surgical time, less tissue manipulation, reduced inflammation, post...
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