New High-speed Vitrector Offers Benefits to Surgeons

The 25-g cutter reduces inflammation and postop recovery challenges.

ROCHELLE NATALONI, CONTRIBUTING EDITOR

Theoretical advantages of sutureless, small-gauge vitrectomy include less traumatic conjunctival and scleral manipulation, less postoperative intraocular inflammation and less postoperative corneal astigmatism.¹ Under optimal conditions, 25-g procedures induce minimal ocular trauma, decrease the inflammatory response, and may allow for overall faster patient recovery.² Transconjunctival surgery using 25-g instrumentation may hasten postoperative recovery by decreasing overall surgical time and postoperative inflammation.²

As the literature shows, less inflammation, reduced postoperative pain and quicker healing are among the benefits of small-gauge sutureless vitrectomy and these features are steadily promoting this technique to standard of care. As more and more retinal surgeons make the transition to sutureless vitrectomy, manufacturers are introducing modifications to their existing high-speed cutters to further increase efficiency and safety.

The Adaptable Vitrectomy Enhancer (AVE) (Figure 1), which is manufactured by Medical Instrument Laboratories, Inc. (MID Labs, San Leandro, CA) and distributed by Bausch & Lomb (B&L, Rochester, NY) in the United States in conjunction with its Millennium Microsurgical System, is 1 example. In this article, a user describes the advantages the AVE offers surgeons.

DELIVERING BETTER VITRECTOMIES

The AVE enables safe, efficient, and effective 20- and 25-g vitrectomies, according to Tarek S. Hassan, MD, Associated Retinal Consultants, Royal Oak, MI, and a consultant to B&L. "The Adaptable Vitrectomy Enhancer answers our need for a small, pneumatically driven, more rigid vitrectomy probe," says Dr. Hassan.

The AVE works by connecting to the Millennium system via the airline to the pneumatic vitrectomy probe port; the probes connect to the AVE via the pneumatic line and the aspiration line to the Millennium cassette. The 3-port, pars plana vitrectomy, which is utilized with the 25-g AVE, simplifies the surgical procedure for the surgeon — because there is no conjunctival opening and no sutures required to close at the end of the procedure — as well as minimizing the intraoperative trauma for the patient. Additionally, it can be used for most posterior segment surgeries, according to the literature. The price of the AVE unit is $9000.

Figure 1. The Adaptable Vitrectomy Enhancer.

NEW-GENERATION IMPROVEMENTS

AVE users say the cutter improves upon the previous generation of high-speed cutters. "Clinically, the 25-g AVE vitrectomy provides function with many similarities to 20-g vitrectomy, while employing much smaller incisions," says Dr. Hassan. He also points out that, ideally, retinal surgeons want superior cutting and flow characteristics in all gauges, but prefer a small, lighter handpiece. "The AVE probe has a much stiffer shaft than first-generation 25-g systems," (Figure 2A and 2B) he explains. "This improves the surgeon's ability to move the eye during surgery and enables surgeons to achieve superior performance with the ergonomic benefits of a small, light, easily manipulatable pneumatic probe."

Figures 2A and 2B. The stiff shaft of the AVE 25-g high-speed vitrectomy system facilitates posterior capsulotomy and easy peripheral access with no flexion.

Dr. Hassan points out original probes were very flexible. "They bent significantly in the eye and were restricted by the amount of add-on instruments that could be used," he explains. "Those probes simply didn't get the job done in a lot of cases and many surgeons soured on 25-g technology because of those experiences. Yet surgeons realized the benefits of going with sutureless incisions."

The 25-g (and 20-g) AVE vitrectomy cutters deliver cut rates of up to 2500 cpm, which reduce vitreoretinal tractional forces and the potential for retinal tears. This high speed also reduces turbulence for enhanced control of mobile tissue. "We can cut more vitreous at a higher speed and cut rate, which makes it a safer procedure because our goal is to cut at as quick a cut rate as possible in order to minimize any pulling on the retina. The guillotine on this cutter is moving so quickly, there is less traction," Dr. Hassan explains. "The AVE is the only 25-g system that allows you to cut at 2500 cpm. If you're cutting vitreous fast enough, it's not bouncing around as much, which essentially means you're not pulling on the rest of the gel in the eye as much."

Another AVE advantage is that it aspirates vitreous more efficiently at a much higher flow rate than previous cutters, according to Dr. Hassan. (Figure 3A and 3B) "This flow rate factor is not as critically important at the 20-g level, but at the 25-g level it is very important," he says. "One of the major criticisms of standard 25-g vitrectomy surgery is how long it takes the cutter to remove vitreous and how inefficient it is compared to a big 20-g cutter."

Optimized pneumatic pressure pulse and an increased port size area are behind the improved aspiration flow in this second-generation pneumatic cutter, the company reports. B&L also says the AVE requires half the pressure to drive the cutter than other pneumatic systems, which affords finer control and results in less vibration. "The port size is significantly larger than the first-generation 25-g pneumatic cutters, and the duty cycle — or the percentage of time that the port is actually open — is much higher than that in comparable first-generation pneumatic cutters," says Dr. Hassan. "Each of those features individually brings out an increased flow."

Figures 3A and 3B. AVE's high flow rate is illustrated here in a case of (A) Peripheral diabetic retinopathy (PDR) with vitreal hemorrhage and; (B) dislocated lens with vitreal hemorrhage.

While the AVE does everything that previous generations of 25-g cutters do, it also exceeds the abilities of previous generations to allow for expanding indications, its proponents claim. "This system enables us to work further out in the periphery because the instrument shaft is much stiffer than the old cutter, and also because it cuts so well," says Dr. Hassan. "Much more peripheral pathology is now more safely accessible with the AVE, including retinal detachments, proliferative diabetic retinopathy, and even proliferative vitreoretinopathy."

Work that needs to be done out in the periphery, with good control and high flow, is well suited to the AVE. "It also lets you do much more with dropped lens material and cataract fragments," says Dr. Hassan. "I've done cases where the entire nucleus — not just lens cortex — has fallen back and the AVE is much better at allowing me to do what needs to be done. It is also possible to perform lensectomy removal of reasonably dense nuclear material, which would have been very difficult to do with prior generations of 25-g technology."

Even in cases of fibrous membranes, the B&L 25-g performs effectively, and the reduction in patient recovery is marked, the literature shows.³ With a 20-g system, patients might have to wait 8 to 10 weeks for stitches to dissolve and induced astigmatism to resolve, whereas with sutureless 25-g surgery, better-than-preoperative vision is commonly seen within a week.³

THE FUTURE IS SUTURELESS

It is true that some retinal surgeons still have not made the leap to sutureless vitrectomy, but Dr. Hassan says, "Whether it takes another 1 year, or 5, or 10 years, I suspect that most will ultimately move in that direction."

Recent studies support his speculation. Dr. Hassan and colleagues did a retrospective study of long-term outcomes of transconjunctival sutureless 25-g vitrectomy. They found that after a mean follow-up of more than 1 year, minimal complications were seen and none were specifically related to the sutureless nature of the procedure. The retrospective, noncomparative, case series entailed a chart review of Dr. Hassan's initial 45 consecutive transconjunctival sutureless vitrectomies, including patients with idiopathic epiretinal membrane, refractory diabetic macular edema, idiopathic macular hole, and nonclearing vitreous hemorrhage. All patients had at least 6-months follow-up, and the main outcome measures included visual acuity (VA), intraocular pressure, intraoperative complications, and postoperative complications. The mean overall preoperative VA vs last postoperative VA was 20/229 and 20/65, respectively, and statistically significant VA improvement was seen for each patient subgroup.¹

In a more recent study, Patelli and colleagues reported on the safety and surgical outcome of 25-g transconjunctival sutureless vitrectomy. They concluded that "The absence of intraoperative complications and relatively low rate of postoperative complications suggest that this technique is safe and effective for treating macular conditions."

In this single-center, retrospective, noncomparative case series, 160 eyes of 150 patients underwent 25-g vitrectomy for different macular conditions: 108 eyes for idiopathic macular pucker, 24 for idiopathic macular hole and 28 for tractional diabetic macular edema. There were no intraoperative complications. However, 3% of eyes had complications during follow-up and 25% of phakic eyes presented with a significant cataract at the 6-month follow-up.⁴

GAUGE CONSIDERATIONS.

An AVE 23-g high-speed cutter is in the pipeline, MID Labs reports, with availability expected this year. However, Dr. Hassan considers 23-g vitrectomy as more of a compromise than evolution.

"With the 23-g, it is possible to make sutureless wounds that are bigger than those made with 25 g, and with different instrumentation that more closely approximate that which is used in 20-g vitrectomy — but the instruments are not as small and the wounds are not as tight as those made with 25 g," he explains. "Something to consider is that this new 25-g AVE cutter might make it a lot less important to need a 23-g cutter for many cases because the 25-g AVE performs so well." RP

REFERENCES

1. Ibarra MS, Hermel M, Prenner JL, Hassan TS. Longer-term outcomes of transconjunctival sutureless 25-gauge vitrectomy. Am J Ophthalmol. 2005;139:831-836.
2. Lakhanpal RR, Humayun MS, de Juan Jr E, et al. Outcomes of 140 consecutive cases of 25-gauge transconjunctival surgery for posterior segment disease. Ophthalmology. 2005;112:817-824.
3. McCary BD, Splinter DC, Edwards KH. Millennium TSV25: System enhancements bring added safety, efficiency and ease of use to 25-gauge vitrectomy. TSV25 White Paper, Bausch & Lomb Inc, 2004.
4. Patelli F, Radice P, Zumbo G, Frisone G, Fasolino G, 25-Gauge macular surgery: results and complications. Retina. 2007;27:750-754.

The ideas and opinions expressed in this article do not necessarily reflect those of the editor, the editorial board, or the publisher, and in no way imply endorsement by the editor, the editorial board, or the publisher.