Guillotine cutters have been the standard tools for performing vitrectomy for decades. They are versatile, and have only gotten better over time. Because of this, when a new technology—hypersonic vitrectomy (Vitesse, Bausch + Lomb)—comes along that can remove vitreous in a different way, surgeons are naturally interested in learning more about its operation, strengths and possible limitations. Since only a few hundred cases have been performed with this technology, however, surgeons still don’t have a lot of day-to-day experience with it. 

In this article, a few of us who have been involved with the development and utilization of hypersonic vitrectomy will try to answer some questions a surgeon might have about it.

 

How Does It Work?
To understand how a hypersonic vitrectomy probe differs from a guillotine cutter, it helps to understand how the latter works. Guillotine cutters have a needle-within-a-needle design (Figure 1). The internal needle cuts the vitreous by moving back and forth; then the vitreous particles are aspirated through the interior lumen of the needle. The evolution of vitreous cutters has led to smaller gauge probes with smaller lumens that can increase resistance and decrease flow. Additionally, with standard guillotine cutters, lower cut rates result in larger particles that can increase vitreous traction and decrease flow. Because of this, we’ve moved to higher cut rates and more efficient cutters that result in smaller particles, which can decrease traction and increase flow. 



Image courtesy of Bausch + Lomb

Figure 1. A pneumatic cutter’s needle-in-a-needle design. The duty cycle is less than 100 percent and, as the lumen narrows, there’s increased resistance to flow. 

The hypersonic vitreous cutter takes a different tack; rather than mechanically cutting the vitreous and then aspirating cut particles, the hypersonic unit uses ultrasonic vibrations, operating at 1.7 million cycles per minute, to liquefy the vitreous gel near the device’s port. The probe of the device is a single lumen shaft with a small port that’s always open, providing a unique 100-percent duty cycle (the amount of time the port is open; Figure 2). The device liquefies the vitreous at the outer margins of the port and then aspirates the resulting microparticles.1

While on a superficial level this technology may seem similar to phacoemulsification, it’s actually quite different. Early in their training, all ophthalmologists learn that a phaco handpiece shouldn’t be used to remove the vitreous because the phaco handpiece doesn’t cut the gel, it aspirates it. This aspiration can cause traction on the retina, which can lead to retinal tears and detachments. In contrast, the hypersonic vitrectomy probe liquefies the vitreous at the port using higher frequency, lower amplitude vibrations. 



Image courtesy of Bausch + Lomb

Figure 2. The hypersonic vitrectomy handpiece has a single lumen shaft, and the port is always open.  


Additionally, the surgeon has control over the oscillation distance of the probe. Longitudinal oscillation in the hypersonic vitrectomy unit (referred to as stroke) ranges between 0 and 60 micrometers. The user can adjust stroke intraoperatively in real time in order to influence the speed and effectiveness of vitreous removal. 

We’re learning more about optimizing stroke settings with each use of the device. For instance, we now know that for performing a core vitrectomy, or removing dense vitreous hemorrhage or retained lens material, having more stroke (liquefying energy) and vacuum is helpful. When we shave the vitreous, however, particularly over mobile retina, we need less stroke and vacuum. Additionally, in our experience, it appears that hypersonic vitrectomy doesn’t require a lot of vacuum to operate efficiently.

A potentially useful feature of a hypersonic vitrectomy handpiece is that the probe can be modified in different ways (Figure 3). Along these lines, curved probes and different port locations are being tested that may be more useful than straight probes in certain situations. For example, it’s difficult, if not impossible, to remove the peripheral vitreous 180 degrees from the sclerotomy site without contacting the crystalline lens. Having a curved tip might enable the removal of this vitreous without hitting the lens.



Image courtesy of Bausch + Lomb
Figure 3. Examples of several tip designs for the hypersonic vitrectomy cutter. The single lumen design means the probe doesn’t need to be straight, which allows flexibility in the shapes of the tips that can be created. 


The hypersonic vitrector runs on electricity, so no pressurized gas—provided by either tanks or in-wall lines—are necessary for its operation. This could be helpful when performing vitrectomy in parts of the world where pressurized gas isn’t available, such as remote areas or less-developed regions served by medical missions.

 

In Vitro Studies

In our own in vitro studies, we’ve found the hypersonic vitrectomy cutter to be associated with smooth and continuous vitreous aspiration, primarily because the port is always open. The hypersonic vitrectomy probe creates little traction on the vitreous as the gel is liquefied around the probe opening.  

In two histopathologic studies of porcine retinas funded by Bausch + Lomb, the instrument appeared to cause less disruption to the inner retinal layers than a pneumatic cutter (Figure 4).2,3

 

Human Experience

The first in-human study was conducted at Dr. Agarwal’s Eye Hospital in Chennai, India by the University of Manchester’s Paulo Stanga, MD,  Amar Agarwal, MD, and colleagues. They described their experience on 20 eyes that underwent vitrectomy for macular hole, vitreous hemorrhage and vitreomacular traction. The surgeons were able to perform core vitrectomy on all eyes with the hypersonic unit, and induced a posterior vitreous detachment in 13 of 15 eyes. The peripheral vitreous was shaved with the hypersonic vitrector in 18/20 eyes. However, one eye with a dense, organized vitreous hemorrhage and another with a retinal detachment had the peripheral gel removal completed with a guillotine cutter. Two eyes developed retinal detachments that were ultimately repaired.4

Recently, our group presented on hypersonic vitrectomy at the 2018 American Society of Retina Specialists Meeting in an effort to describe the technology’s performance and provide a sense of the pathologies it could be used for.5 We performed a prospective, multicenter, non-randomized case series of 71 eyes in 71 patients using five different surgeons. We looked at such variables as intraoperative energy (stroke length and time) and fluid usage. The surgeons were also polled regarding the usefulness of the technology, complications and its potential advantages or disadvantages.



Image courtesy of Kevin Binder, MD, and Carl Awh, MD 

Figure 4. Histopathology of a pig eye post-hypersonic vitrectomy. There is minimal disruption to the inner retinal layers.  

The surgeons found that hypersonic vitrectomy could be used for a variety of vitreoretinal cases, including retinal detachment repair, silicone oil aspiration, macular surgery, diabetic traction detachments and removal of retained lens material. The surgeons found that the average vitrectomy actuation time (the time spent stepping on the activation pedal to liquefy vitreous or remove fluid from the vitreous cavity) was approximately 5.5 minutes. In 97 percent of cases, there were no intraoperative complications, although there was one case of a small iatrogenic retinal break in a detached retina, as well as some superficial scoring of the posterior intraocular lens surface (outside the visual axis) during capsulotomy in another eye.

In nearly 90 percent of cases, vitrectomy was performed entirely with the hypersonic vitrectomy probe. However, in cases of traction retinal detachment with thick diabetic membranes, and cases that had a taut posterior hyaloid, some of the study’s surgeons preferred the guillotine cutter. The results were similar to a hypersonic probe, however.

The surgeons described little traction when shaving the peripheral vitreous near areas of mobile retina when using hypersonic vitrectomy. Decreased traction is particularly valuable when working near mobile detached retina, and hypersonic vitrectomy doesn’t appear to induce much traction as it liquefies the gel. Hypersonic vitrectomy may also be useful in cases of retained lens material, in which the device has been shown to be effective enough to eliminate the need to use a fragmatome, even in cases with dense lens material. Interestingly, the hypersonic device can also remove 1,000 cs and even 5,000 cs silicone oil, possibly eliminating the need for separate silicone oil removal devices.  

In conclusion, hypersonic vitrectomy represents a new way of removing vitreous gel that may have unique strengths that surgeons can take advantage of. However, as with any new technology, much work remains in order to optimize its use, such as determining its optimal settings, how to adjust stroke and vacuum for different pathologies and creating different probe designs. Guillotine vitrectomy probes have improved over the past 40 years due to continuous research, development and routine use. We’re optimistic that hypersonic vitrectomy will rapidly improve as well, and be able to achieve excellent outcomes for patients with a variety of intraocular pathologies. REVIEW

 

Dr. Garg is a professor of ophthalmology at the Sidney Kimmel Medical College at Thomas Jefferson University, an attending physician on the Retina Service at Wills Eye Hospital in Philadelphia, and a partner with MidAtlantic Retina. Dr. Blinder is a professor of clinical ophthalmology & visual sciences at Washington University School of Medicine. Dr. Awh practices at Tennessee Retina in Nashville.

The authors are consultants to Bausch + Lomb.

    

1. Stanga PE, Pastor-Idoate S, Zambrano I, Carlin P, McLeod D.  Performance analysis of a new hypersonic vitrector system.  PLoS One 2017 Jun 6;12:6:e0178462. doi: 10.1371/journal.pone.0178462. eCollection 2017.  PMID:  28586375

2. Ch’ng SW, Irion LD, Bonshek R, Shaw J, Papayannis A, Pastor-Idoate S, Stanga PE.  Live porcine thirty days delayed recovery surgery: Qualitative findings with the hypersonic vitrectomy. PLoS One 2018 Jun 1;13:6:e0197038. doi: 10.1371/journal.pone.0197038. eCollection 2018. PMID: 29856756

3. Pastor-Idoate S, Bonshek R, Irion L, Zambrano I, Carlin P, Mironov A, Bishop P, McLeod D, Stanga PE.  Ultrastructural and histopathologic findings after pars plana vitrectomy with a new hypersonicvitrector system. Qualitative preliminary assessment.  PLoS One 2017 Apr 11;12:4:e0173883. doi: 10.1371/journal.pone.0173883. eCollection 2017. PMID: 28399127

4. Stanga PE, Williams JI, Shaarawy SA, Agarwal A, Venkataraman A, Kumar DA, You TT, Hope RS.  First in human clinical study to investigate the effectiveness and safety of pars plana vitrectomy surgery using a new hypersonic technology.  Retina 2018 Oct 23. doi: 10.1097/IAE.0000000000002365. [Epub ahead of print.  PMID: 30358763

5. Garg SJ, Blinder K, Awh C, Tewari A, Srivastava S, Kolesnitchenko V.  The utility of hypersonic vitrectomy settings in vitreoretinal surgery. July 22, 2018. American Society of Retina Specialists Annual Meeting. Vancouver, Canada.