First Impressions With 27-gauge Vitrectomy

A review of the smallest-gauge vitrectomy instruments, which are finally available in the United States

M. ALI KHAN, MD • CARL. D. REGILLO, MD, FACS

Microincision vitrectomy surgery (MIVS) has all but replaced 20-gauge equivalents, offering benefits such as faster visual recovery and reduced postoperative inflammation.¹ In the 2013 ASRS Preferences and Trends survey, 96.3% of retinal specialists in the United States noted use of 23- or 25-gauge MIVS systems.²

With the commercial introduction of 27-gauge instrumentation by Alcon (Fort Worth, TX, Figure 1) and Dutch Ophthalmic (Exeter, NH, Figure 2), use of this technology is rising. In this article, the initial experience and current evidence regarding the use of 27-gauge vitrectomy is described.

Figure 1. Alcon’s Constellation 27-gauge victrectomy system.

Figure 2. Dutch Ophthalmic’s 27-gauge vitrectomy system.

INITIAL EXPERIENCE

Oshima et al³ first described use of a 27-gauge vitrectomy system in 2010, describing the outcomes in a series of 31 eyes in Japan. Comprised of largely macular cases, no intraoperative or postoperative complications were encountered.

Rizzo et al⁴ later reported a series of 16 patients in Italy who underwent 27-gauge vitrectomy for more varied surgical indications, including diabetic tractional retinal detachment and rhegmatogenous retinal detachment, and they also reported favorable outcomes.

In these initial 47 cases published in the literature, no cases required conversion to 20-, 23-, or 25-gauge instrumentation, and surgical success was achieved in all cases.

SHORT-TERM OUTCOMES

In a retrospective, multicenter study of 95 eyes, our institution, in conjunction with several other centers in the US, described the largest series evaluating short-term outcomes with use of the commercially available Alcon Constellation 27-gauge MIVS system (Figure).⁵

At a mean follow-up of 144 days, favorable visual and anatomic outcomes were reported across varied surgical indications, including epiretinal membrane, diabetic tractional retinal detachment, macular hole, rhegmatogenous retinal detachment with or without proliferative vitreoretinopathy, vitreous hemorrhage, vitreous opacities, endophthalmitis, retained lens material, submacular hemorrhage, and aqueous misdirection.

Overall, visual acuity improved significantly from 20/240 preoperatively to 20/67 at final follow-up (P<.001). Similar to Oshima et al and Rizzo et al, no cases required conversion to larger-gauge instrumentation. One sclerotomy site in three different eyes (1.1% of total sclerotomy sites) was sutured to ensure wound closure, and no cases of endophthalmitis, sclerotomy-related retinal tears, or choroidal detachments were encountered.

Transient hypotony, defined as new onset intraocular pressure ≤6 mm Hg, occurred in 5 eyes (5.3%) with spontaneous resolution by postoperative day 7.

Overall, the observed complication rates were comparable to prior studies utilizing 23- and 25- gauge systems,^1,6-8 including, with regard to hypotony and rate of sclerotomy site, suturing for wound closure.

POTENTIAL BENEFITS

Experimental models utilizing 27-gauge instrumentation have identified potential benefits to using the technology. With regard to design, 27-gauge cutters feature smaller port diameter and port depth, with port placement very close to the end of the probe (0.2 mm with the Alcon Constellation 27+ cutter). Such changes allow for improved access to preretinal membranes, potentially permitting the cutter to serve as a dissection instrument for cases in which extensive membrane peeling is required, such as diabetic tractional detachment.

In addition, Dugel et al⁹ showed that smaller-gauge vitrectomy probes have shorter membrane attraction distances and a reduced “sphere of influence,” limiting disruption of surrounding tissue and potentially reducing iatrogenic retinal breaks.

Wound Construction

With both 25- and 23-gauge vitrectomy systems, adoption of a two-stage, angled trocar incision improved wound integrity and reduced wound-related concerns, which were initially present with sutureless, small-gauge vitrectomy.^10,11 With the advent of 27-gauge technology, however, angled incisions may no longer provide an observed benefit.

In the series reported by Oshima et al and Rizzo et al, all of the incisions were one-stage, straight incisions.^3,4 No sclerotomy site required sutures for closure, and no wound-related complications, such as hypotony, endophthalmitis, or serous choroidal detachment, were noted.

In our multicenter series, comparison of angled vs straight incisions was performed. An angled approach was utilized in 72% of cases and a straight approach in 28% of cases in that series.⁵ A total of three sclerotomy sites required sutures for closure, and no significant difference in IOP or postoperative complication rate was noted between eyes with angled vs straight incisions.

The results suggested that both wound construction techniques could be used effectively with 27-gauge instrumentation, allowing surgeons to choose. To further clarify wound construction strategy with 27-gauge technology, a prospective study is currently under way at Wills Eye Hospital to more directly compare outcomes with angled vs straight incisions.

But Is It Slow? Operative Time With 27-gauge Vitrectomy

A reduced flow rate is inherent to the use of small-gauge instrumentation, causing many to question whether 27-gauge vitrectomy results in longer operative times. Two series have addressed operative times to date.

In a retrospective fashion, our multicenter series found that mean operative time across all eyes (32 minutes) was not significantly different from the mean operative times published for an initial series evaluating 23-gauge (31.9 minutes),⁵ while the authors noted that the use of dual-pneumatic probes may preserve flow rates despite smaller-gauge instrumentation

More recently, Mitsui et al¹² prospectively compared operative times between 27- and 25-gauge vitrectomy for ERM. The authors found that, while total overall operative time was not significantly different between 27-gauge and 25-gauge systems (20.2±9.9 vs 16.1±9.3 minutes, respectively, P=.14), mean vitrectomy time was longer with 27-gauge instruments (9.9±3.5 vs 6.2±2.7 minutes, respectively, P<.0001).

While further prospective study will be necessary to confirm differences in operative time, current evidence suggests that surgery with 27-gauge vitrectomy may not be significantly longer than with 23- or 25-gauge equivalents.

Case Selection and Learning Curve

As experience with 27-gauge technology grows, many surgeons have identified surgical indications that may be particularly suitable for 27-gauge instrumentation. Diabetic tractional detachment, for instance, may highlight the benefits of the 27-gauge cutter, potentially obviating the need for additional dissection tools, such as scissors during surgery. Moreover, the 27-gauge cutter may be used in combination with 23- and 25-gauge systems, allowing for independent use of the cutter when desired.

In contrast, an illuminated endolaser probe is currently unavailable for use with 27-gauge technology. For this reason, some surgeons may pause when considering use of 27-gauge instrumentation for cases in which peripheral endolaser is expected, such as in retinal detachment cases or when a skilled surgical assistant is unavailable. The work-around in such instances would be the use of chandelier lighting.

In addition, similar to initial concerns with the use of 25-gauge MIVS, flexibility is a common concern with the use of 27-gauge instrumentation. To date, 27-gauge MIVS has been successfully utilized across the spectrum of vitreoretinal surgery indications, indicating that the instruments are of sufficient stiffness to perform all necessary maneuvers.

Care should be taken to avoid excessive bending of instruments, although some bending is to be expected, particularly with early experience and with the use of noncontact, widefield viewing, with which the surgeon is more dependent on rotating the globe to view the far periphery.

CONCLUSIONS

The use of and experience with 27-gauge vitrectomy are rising. Experience to date in the field remains limited, with the technology being commercially available for less than two years. Additional study, with direct comparison to 23- and 25-gauge instrumentation and longer follow-up, will be necessary to better determine the advantages of 27-gauge technology, compared to larger-gauge vitrectomy instrumentation. RP

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