Update on Portable Vitrector Technology and Applications
New devices are increasing the efficacy of in-office vitrectomy.
BRIAN C. DOYLE, MD · JOHN D. PITCHER, III, MD
Brian C. Doyle, MD, is a resident in ophthalmology at the Wills Eye Hospital in Philadelphia, PA. John D. Pitcher, III, MD, is a fellow in vitreoretinal surgery at Wills and a clinical instructor at the Thomas Jefferson Univeristy Hospital, Philadelphia. Neither author reports any financial interest in any of the products mentioned. Dr. Pitcher can be reached via e-mail at firstname.lastname@example.org.
Since its introduction in 1971 by Machemer, vitrectomy has evolved from a single-port procedure using a multifunction instrument1 to two- and three-port instrumentation2,3 of successively smaller sizes.
The number of vitrectomies performed annually has increased substantially over the past 15 years. This is partly due to the declining use of the scleral buckle and partly to the rising numbers of surgeries for macular pathology.4 As experience with small-incision sutureless vitrectomy has increased, 23- or 25-gauge platforms have been widely adopted.5
Three-port pars plana vitrectomy has overwhelmingly been the preferred procedure for nearly 40 years, but more recently, interest has turned back to using fewer ports for select clinical indications. The benefits of using fewer ports include minimizing complications and potentially moving some vitrectomies into an office setting.6
Equipment manufacturers have created new vitrectomy systems that give surgeons the flexibility to decide on the most appropriate location to perform vitrectomy. This article will review the technology and potential clinical uses for portable vitrectors.
In this article, we define a portable vitrector as any vitrectomy unit that is easy to transport between the operating room and office, is compatible with office-based vitrectomy, and can run on battery power.
A review of existing products meeting these criteria yields two distinct categories. The first is designed solely for single-port PPV using a multifunction instrument, while the second category comprises fully functional vitrectomy units no larger than a briefcase.
The first vitrector designed for office use was the Visitrec (Beaver Visitec, Waltham, MA), designed by Robert Josephberg and introduced in 1994.7 This concept gradually transformed into the now commercially available Intrector (Insight Instruments, Inc., Stuart, FL).
Figure 1. Schematics of the Intrector dual-lumen probe.
Figure 2. Intrector control box and probe.9
The Intrector is a 1,200-cuts-per-minute (CPM) guillotine-style vitrector with dual-lumen 23-gauge probe. The probe contains a central infusion channel and peripheral aspiration/cutter channel connected to a 3-mL syringe for manual aspiration (Figures 1 and 2).
A newly designed probe, the Retrector, incorporates a retractable 23-gauge needle for insertion with a blunt-tipped cannula aimed at making peripheral vitrectomy safer. Either a binocular indirect with 20 D lens or an operating microscope provide illumination.
The fluidics of the Intrector have been investigated using water and egg white, with results showing slightly lower generated vacuum than traditional console systems (120-135 mm Hg vs 250-600 mm Hg) and equivalent aspiration flow rates (0.39 mL/min vs 0.29-0.9 6mL/min).8
Aspiration l ow rate increases with cutter speed, and the model tested had a maximum of 600 CPM. The newer 1,200 CPM model may consequently have aspiration flow rates greater than those quoted in the paper.
The fluidics were comparable to commercially available vitrectors. The paper concluded that the Intrector can achieve a safe range of vacuum and aspiration flow rates.
Hilton first reported on the use of the Visitrec with a series of 225 patients, the vast majority of whom had endophthalmitis.7 The procedure was reportedly well tolerated with low complication rates, including one case of retinal tear (0.4%), five cases of hyphema (2.2%), and four cases of vitreous hemorrhage (1.8%).
The authors postulated that the complications were due to hypotony, because they did not initially replace vitreous with a similar volume of fluid. The procedure was also used for a limited number of pneumatic retinopexies with large-volume gas bubble, lens fragment removal, and vitreous biopsy for uveitis.
Koch subsequently reported on the largest series of patients to undergo single-port office-based vitrectomy with the Intrector. More than 4,500 patients were retrospectively reviewed. The majority (80%) had vitrectomy for space-creating purposes in multidrug therapy for exudative AMD.10
Other indications the study included were endophthalmitis, pneumatic retinopexy, and vitreous hemorrhage. Endophthalmitis occurred in nine patients (0.17%), with six noted as being sterile, associated with triamcinolone, and spontaneously resolving. Only two (0.04%) culture-proven cases were noted, which is similar to the rates reported in the literature for 23-gauge vitrectomy.11
Also included were three (0.06%) cases of intraoperative retinal detachment. Cases of intraoperative retinal breaks were not reported separately.
The rates of intraoperative retinal breaks with three-port microincision PPV range from 1.6% to 12.7%.12’13 The authors concluded that single-port PPV using the Intrector could be considered as an alternative to a three-port PPV in carefully selected clinical situations.
The second category of portable vitrector includes full-function vitrectors that are small enough to be easily transported and set up. Two new entrants into this class are the VersaVit (Synergetics, O’Fallon, MO) and the ProCare Plus Vitrectomy System (VisionCare Devices, Inc., Anderson, CA).
VERSAVIT AND PROCARE
The VersaVit is a 2,500 CPM pneumatic vitrectomy system with built in dual LED illumination and the ability to use either a CO2 cannister or compressed air (Figure 3). It weighs 25 lbs, has a built-in handle for easy portability, and can run on battery power.
Figure 3. VersaVit: front (top left), back (bottom left), and wheeled carrying case (right).15
Outcomes from a pilot evaluation were presented at the annual scientific meeting of the ASRS in 2012, showing good performance during six cases in an ASC and one in an office with retrobulbar block and diazepam 10 mg PO for anesthesia.14
The ProCare Plus Vitrectomy System is a 3,000 CPM pneumatic vitrectomy system utilizing a medical air connector and built-in LED illumination (Figure 4, page 34). It is available in AC and battery-powered versions and is incorporated into a briefcase-style carrier. Both systems are marketed as lower-cost alternatives to standard console systems with an emphasis on flexibility and suitability to function as either a primary or backup system. The ProCare Plus was approved by the FDA in May 2012, while the VersaVit was approved in June 2012.
ADVANTAGES AND APPLICATIONS OF OFFICE-BASED VITRECTOMY
Office-based vitrectomy must by definition be tolerable under local anesthesia. Colluciello suggested that a short operative time and a smaller number of incisions contribute to tolerability in the office.17
To test this hypothesis, he performed two-port PPV on 12 patients with PDR and nonclearing vitreous hemorrhage (VH). Clearance of hemorrhage was obtained in all cases without rebleed, and the authors postulated that the procedure could be accomplished in the office.
Figure 4. ProCare control panel (left) and case (right).16
Gualtieri went one step further in performing single-port PPV with infusion through a limbal incision after posterior capsulotomy (if pseudophakic) or anterior and posterior capsulotomy with cataract extraction (if phakic).6 Thee patients reportedly tolerated the procedure well, and the author stated that with proper patient selection, the procedure could be performed in the office.
Two-thirds of Koch’s patients had single-port vitrectomy with the Intrector in the office as described.10 The purported advantages of one- or two-port office-based vitrectomy include shorter procedure times, lower cost, and potential for fewer sclerotomy-related complications (endophthalmitis, retinal tear, hypotony, vitreous incarceration).6,7,17
Indications for Office-Based Vitrectomy
The indications for office-based vitrectomy are not welldefined. The most established uses are for vitreous sampling in endophthalmitis and uveitis.
Vitrectomy in endophthalmitis carries a good risk-reward profile as the patient is most often pseudophakic and visual potential is guarded at the outset. The Endophthalmitis Vitrectomy Study demonstrated beneit of vitrectomy to eyes with light perception vision or worse, and an investigation into the outcomes of in-office vitrectomy in these eyes would be very informative.18
In-office vitrectomy for cases of vitreous hemorrhage could produce faster visual recovery and allow earlier application of laser without a trip to the operating room.
Floaterectomy is a controversial procedure. However, minimally invasive single-port vitrectomy has the potential to give the most benefit with theoretically less risk than standard three-port PPV. Koch reported significant improvement in NEI-VFQ-25 scores in a series of 20 patients with symptomatic floaters treated with single-port vitrectomy.19 Three patients required subsequent three-port limited PPV, and there were no complications at one year.
Cases requiring more extensive vitrectomy or membrane peeling have yet to be proved feasible in an office setting, and the advantages of performing these procedures outside of the operating room are much less apparent.
Although the vast majority of vitrectomies will likely continue to occur in an operating room, the combination of emerging portable vitrector technology and ever-evolving minimally invasive surgical techniques will make office-based vitrectomy possible for carefully selected patient populations.
Some of the more promising indications include endophthalmitis, vitreous biopsy in uveitis, vitreous hemorrhage, vitreous opacity removal, and enhanced pneumatic retinopexy. Further study of outcomes, tolerability, and cost-effectiveness are needed, however, before these procedures become commonplace in the office. RP
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