American Academy of Ophthalmology Web Site: www.aao.org
The Progress of Minimally Invasive Vitreous Surgery
Thanks to little revolutions in technology and technique, contemporary vitrectomy is achieving better outcomes for patients and surgeons alike.
Many surgeons agree that sutureless, small-incision surgeries make for happier, quieter eyes in the vitreoretinal patient. The advantage over larger-gauge procedures comes primarily from reduced postoperative inflammation at the sclerotomy site, leading to speedier recovery. But that’s not all—the operating time is reduced, which, of course, cuts costs, and the small incisions are especially appropriate for working on the eyes of children. Although originally used for macular diseases, 23- and 25-gauge surgeries have progressed so much in recent years that they are the approach-of-choice for most vitreoretinal procedures.
The smaller gauges have not been without frustrations: Instrumentation was originally clumsy (but has gotten much better), and some surgeons encountered quite a learning curve going from 20-gauge to smaller-gauge procedures. And smaller incisions are not automatically the optimal choice. In fact, 20-gauge surgery is still wisely used in a number of situations.
What follows is a look at both the benefits and bumps in the road, along with some advice on managing—or, better yet, avoiding—complications of small-gauge surgery.
A Bounty of Benefits The advantages of small-gauge, sutureless incisions are varied and range from the comfort of the patient to the cost and satisfaction for the surgeon. Here are three prominent attractions of going smaller.
Problems Addressed Progress never arrives without problems, and in the early days of sutureless, small-incision vitreous surgery, surgeons were hampered by limited options for illumination and other instrumentation and a steep learning curve.
Choices in instruments expanding. Illuminated instruments were especially unhelpful for 25-gauge procedures, which could accommodate fewer light fibers. But today this is much less of an issue, especially with the introduction of the illuminator in Alcon’s Constellation Vision System, which boasts a bright light, said Dr. Arevalo.
Surgeons were once also limited to forceps for the smaller vitrectomies. “But several different companies started to develop instruments to work with the smaller systems,” said Dr. von Fricken. These now include Bausch & Lomb’s 23- or 25-gauge Millennium system; Alcon’s 23- or 25-gauge Accurus and Constellation Vision systems; and Dutch Ophthalmic Research Centre’s 23- and 25-gauge systems.
Today, it is easy to find a wide range of vitreous cutters, chandeliers, curved scissors, microvitreoretinal blades, aspirating picks and endoscopic laser probes for both 23- and 25-gauge. This, in turn, has made it possible to expand the indications for these procedures, said Dr. von Fricken. “Now we can do most cases with either 23-gauge or 25-gauge.”
Vitreous cutters have made an especially notable difference in the small-incision experience: The opening of the vitreous cutter is closer to its tip, said Dr. Arevalo, which has allowed for a closer vitreous shave and less risk to the retina. Sometimes the surgeon can dispense with the vitreous cutter altogether, he added, which makes for a simpler, quicker procedure.
One notable absence in the 23- or 25-gauge armamentarium is an ultrasound fragmatome for handling the crystalline lens, said Dr. Arevalo. “Now when we need to phacoemulsify the lens, we have to open a 20-gauge sclerotomy to insert the fragmatome,” he said, adding that this requires opening the conjunctiva, which can lead to suturing to avoid complications.
Learning curves—25G vs. 23G. “What I liked initially about 25-gauge vitrectomy was the cutter and the fluidics,” said Dr. von Fricken. “But it took some time to get used to the instruments being more flexible and the trocars pulling out on occasion.” He gradually expanded to doing almost all retinal detachment surgeries with 25-gauge instrumentation and found no significant differences in outcomes when comparing small-gauge retinal reattachment surgeries with surgery using 20-gauge instruments. Dr. von Fricken said that 25-gauge vitrectomy is ideally suited for macular surgeries, most diabetic vitrectomies and retinal detachment procedures. He suggests that surgeons approach the 25-gauge surgery much like learning to play a musical instrument: “One has to practice.”
Because of its similarity to 20-gauge in terms of rigidity, lighting, flow and aspiration of the vitreous cutter, 23-gauge might be an easier switch and have a smaller learning curve for some, said Dr. Arevalo, who uses it for about 80 percent of his cases. Although flexibility of the 25-gauge can be a problem, he said this should become less of an issue now with the introduction of the Alcon 25+ line of instruments.
Picking up the pieces. Aside from instrument stiffness, which is particularly helpful when doing peripheral endolaser, said Dr. Spirn, the 23-gauge system offers another advantage. “I think 23-gauge is also helpful when doing fragmentation because it’s easier to remove the fragments, which you can sometimes do without a fragmatome.”
Some surgeons think of the 23-gauge as the best of both worlds: stiffness combined with the sutureless approach. But others disagree. “I tried some 23-gauge but didn’t see any real advantage,” said Dr. von Fricken. “I was already used to the 25-gauge instruments and felt that the smaller holes in the sclera led to a lowered risk of wound leaks and postoperative hypotony.”
Dr. Charles said the rigidity problem was overstated from the beginning. “Now, improvements in the Alcon 25+ system put it in the range of 23-gauge in terms of illumination, fluidics and rigidity,” he said. “It’s worth a second try for those who used early 25-gauge technology and have never gone back to reevaluate it.”
Complications, and Tips for Reducing Them An ongoing controversy regarding the correlation between hypotony and endophthalmitis surrounds small-gauge vitrectomy. But, “Hypotony never caused endophthalmitis,” asserted Dr. Charles. “What causes endophthalmitis are vitreous wicks. It’s true that there is some correlation with softer eyes, but it isn’t that there’s a wound leak. If you have a wound leak, the aqueous runs out the hole. But if you leave the sclerotomy filled with vitreous, thinking that somehow plugs it, then vitreous hangs out the conjunctival space. That’s what causes endophthalmitis.”
Dr. Spirn wants the complication rate quantified. “I think the biggest remaining hurdle is clarifying the rate of endophthalmitis and trying to reduce the rates with small-incision surgery,” he said, adding that studies have shown anywhere from an equal risk to a 28-fold greater risk of endophthalmitis with 25-gauge vitrectomy compared with 20-gauge.1 This has prompted some to stay put with 20-gauge procedures, he said.
Fortunately, several techniques have emerged to address concerns about complications:
Is 20-Gauge a Dying Breed? Given the benefits of smaller-incision procedures, why do surgeons continue to perform 20-gauge vitrectomy?
Dr. Arevalo said that although it commands a very small percentage of his cases now, 20-gauge still has a role for complicated cases and for those situations when opening the conjunctiva and sclera is necessary, such as for scleral buckling and phaco fragmentation.
Right after the advent of the 25-gauge, Dr. Charles introduced the idea of the 20-25 hybrid vitrectomy for that very purpose: fragmenters were only available for 20-gauge. “So I enlarged one wound, introduced the fragmenter and took out the lens material,” he said. “Then I invented an adapter—basically a sleeve with a flange on it—which you can put in the now-enlarged wound and make it small again to finish the vitrectomy.”
Other than this, Dr. Charles prefers 25-gauge over 20-gauge in all cases. “This isn’t some kind of specialized technique only for certain cases,” he said. “A major misconception in the vitreoretinal community, one which I’d like to dispel, is the notion that it’s all about cherry-picking easy cases to do this way and that if it’s a retinal detachment or a diabetic traction retinal detachment, you should do it the conventional 20-gauge way. That’s simply incorrect.”
Drs. Arevalo and Spirn do, however, also prefer the hybrid for removal of silicone oil. “I find that doing oil removal through 23- or 25-gauge is tedious, that it’s not always easy to remove it all,” said Dr. Spirn. “I use an 18-gauge angiocatheter to remove the oil. Even with 1,000-centistoke oil, I think it’s advantageous to do a hybrid.”
Dr. Charles, on the other hand, no longer uses a hybrid with silicone oil. He favors 1,000-centistoke oil, given that it’s less viscous and there’s no evidence, he said, that it’s inferior to 5,000. Dr. Charles said he finds it possible now to do all silicone oil cases by 25-gauge, with the help of the MedOne Viscous Fluid Injection system.
With many technological advances and with varied instruments and enhancements in technique, small-incision vitrectomy has clearly made its mark on vitreoretinal surgery.
A Quick History and Future of Small-Gauge Vitrectomy
Introduced by Robert Machemer nearly 40 years ago, the predecessor to sutureless vitreous surgery was 17-gauge pars plana vitrectomy using a multifunctional vitrector through a single port.1 During the 1980s and ’90s, the standard of care became a three-port pars plana sclerotomy system using 20-gauge instrumentation. 2 Described by J. C. Chen, sutureless PPV for 20-gauge instruments first came on the scene in 1996.3 At that time, introducing instruments through a self-sealing, scleral-tunnel sclerotomy was a novel approach, if not without challenges. Complications such as wound leakage, vitreous incarceration and retinal tears ensued. And conjunctival dissection and suturing were still often required.4
Then the introduction of small-trocar cannulas paved the way for greater advances in vitreoretinal surgery. In 1990, Eugene de Juan developed 25-gauge instruments, but the 25-gauge transconjunctival sutureless vitrectomy wasn’t introduced until 2002 by G. Y. Fuji.2 Sharing characteristics of both its forerunners, 23-gauge vitrectomy soon followed, developed by Claus Eckardt, in 2005.4 It was smaller than 20-gauge but more rigid than 25-gauge, making procedures such as endolaser and shaving of the vitreous gel easier for some surgeons.2
Going Even Smaller? The 27-gauge vitrectomy, not yet available in the United States, got its start in Japan, where it’s being used on a limited basis for procedures such as macular surgery or floaters, said Dr. Charles.
There are some questions among U.S. ophthalmologists on how small is too small. “If there is a way to make 27-gauge comparable in terms of stiffness to 23-gauge or 25-gauge, then I think people will move toward smaller instrumentation,” said Dr. Spirn. Dr. von Fricken, however, said there comes a point of diminishing returns. “As you make smaller openings, you’re violating the eye less, but it’s also more difficult to fit through the port the instruments you need to accomplish your tasks,” he said. “At what point is the gauge too small to be effective?”
“I’ve used the 27-gauge in the lab, and it works great,” said Dr. Charles, although he concedes that it’s still not clear whether it will be useful for the most difficult diabetic traction retinal detachments. “Certainly, we won’t be able to use it for lens material that is dislocated in the back of the eye after difficult cataract surgery.”