Getting Started With 23-g Vitrectomy
Surgeon calls 23 the "Goldilocks gauge: not too big, not too small, just right."
Paul Tornambe, MD, spoke at the 2006 Retinal
Physician Symposium (May 31-June 3, 2006, Atlantis, Paradise Island, Bahamas) about
23-g vitrectomy, calling 23 "the Goldilocks gauge: not too big, not too small, just
right." Vitreoretinal surgeons should definitely be moving toward smaller-gauge
instruments, he said.
"23-g gives us more control, is safer and should improve outcomes." Dr. Tornambe said he has concerns about the smaller, 25-g instruments.
PROS/CONS OF 25-G VS. 23-G
The incidence of endophthalmitis appears to be higher for 25-g surgery, Dr. Tornambe said, and he cited a report by David Williams, MD, of a high incidence of retinal detachment in his 25-g procedures for vitreous floaters. "He attributed that to the fact that he was not able to dissect the vitreous base very well," Dr. Tornambe said. He also questioned whether surgeons are focusing too much on how the patient will look after surgery, perhaps forgoing perioperative antibiotics and using 5% betadine when they should be using 10%.
"So is 25-g really worth the risk?" he asked. "It is faster than 20-g; it is sutureless; there is less postoperative discomfort; and eyes are nice and clear the next day. But I think we have to look at these risks and be a little bit more honest and get away from the plastic surgeon mentality that the patient is going to look pretty the next day."
On the other hand, 23-g surgery is no-compromise surgery, Dr. Tornambe said. In his experience, it is a more controlled vitrectomy; the instruments do not bend; peripheral dissection can be done just as well as with 20-g instruments; the illumination is excellent; and with the Eckardt 23 Gauge Vitrectomy System (from Dutch Ophthalmic Research Center [DORC], the only complete 23-g system available at press time) the procedures are also primarily sutureless.
Furthermore, 23-g surgical procedures are not "training wheels" for 25-g, Dr. Tornambe said. "That is nonsense because the feel of the 23-g instruments is almost identical to that of 20-g instruments. The trocar system is simple. And I think it is much less traumatic than the early 25-g units. 23-g is a step away from 20-g, but once you master 23-g, you are no better at performing 25-g. There is no association between the two."
GETTING STARTED WITH 23-G SURGERY
Dr. Tornambe suggested that surgeons interested in transitioning to 23-g surgery set up their next 20-g cases as they normally would, but use some 23-g instruments, such as a cutter, a pick or forceps, during the course of the cases. "See what the 23-g feels like," he said. "If the case becomes uncomfortable, you can put your 20-g instruments back in to finish. Once you feel comfortable, I think you will find the 23-g instruments are much more elegant than the 20-g. Then you can go ahead and try the Eckardt system."
OPTIONS FOR INFUSION
|Figure 1. The sharp, 23-g self-retaining, self-sealing cannula can be used for 20-g cases. It requires no sutures to fixate or close.|
According to Dr. Tornambe, surgeons have four options for infusion in 23-g cases:
1. The Eckardt system makes a beveled incision that can be a challenge to master but may reduce the risk of endophthalmitis.
2. The blunt, nondisposable, self-retaining cannula that he developed with DORC, which requires a 23-g sclerotomy.
3. The sharp, self-retaining, disposable cannula (Figure 1), which
he also helped develop, is inserted like a thumbtack without the need to first make
23-g sclerotomy. "It is a single pass right through the conjunctiva and sclera," he explained. "You can use the 23-g cannula even if you are doing a 20-g case because the infusion flow will keep up with a 20-g cutter. So if you do not want to move to the complete 23-g or 25-g setup, you can still decrease the number of sutures you use by a third just by using a 23-g infusion cannula."
4. The blunt-tipped, self-retaining, reusable side port infusion, which also requires a sclerotomy. "It has little notches on the hub, so it tells you where it is forcing the fluid or air to go," Dr. Tornambe said. "It directs air sideways, not directly onto the retina and optic nerve, which may minimize the risk of postoperative scotomas."
A new 23-g system from Alcon is expected on the market soon, but the DORC vitrector is available now, Dr. Tornambe said. The DORC handpiece can be used with the current Alcon pneumatic vitrectomy unit as long as the Alcon collection canister is also used.
"The smaller port means a safer vitrectomy," Dr. Tornambe said, "because you are not sucking in as much fluid. Also you decrease your dependence on scissors." Dr. Tornambe typically uses a suction level between 300 and 600 mm Hg.
The 23-g forceps available today do not bend in the eye and are more elegant than the 20-g forceps most surgeons are accustomed to, Dr. Tornambe said. "Again, when you are doing a 20-g case, an internal limiting membrane peel, for example, try a pair of 23-g forceps to see for yourself that the smaller tips make the peel easier."
Dr. Tornambe also outlined the pros and cons of the illumination options for 23-g surgery, which are currently a focused handheld probe, a nonfocused handheld probe or a scleral fixated chandelier (25-g).
In his experience, a focused probe provides good illumination and is the best way to see the vitreous and retinal surface highlights and shadows, but it provides a poor panretinal view, raises the issue of phototoxicity and requires the use of a hand.
"If one hand is holding a light, you cannot perform bimanual surgery unless you have picks on the probe," Dr. Tornambe said. "I personally have never felt comfortable with a bayonette on the end of a light."
He finds a nonfocused probe to be adequate for panretinal viewing and less likely to cause phototoxicity, but more difficult for viewing unstained vitreous and retinal highlights. "You have to use Kenalog or fluorescein to see the vitreous well with a nonfocused probe," he said.
Chandelier illumination permits bimanual surgery, provides a wide field of view and low chance of phototoxicity, but it also makes visualization of unstained vitreous and retinal highlights difficult, he said. Given the strengths and weaknesses of each lighting option, Dr. Tornambe typically uses a focused probe for working with an internal limiting membrane or an epiretinal membrane or dissecting the vitreous base.
He uses a chandelier in difficult cases of proliferative diabetic retinopathy, proliferative vitreoretinopathy, where bimanual surgery is needed, and cases he is recording. At times, he uses both a focused probe and a chandelier light. "I tend to use both when I need to keep track of the retina outside the view of the focused light probe during complicated dissections," he said.
USING THE 23-G ECKARDT SYSTEM
Discussing the Eckardt 23 Gauge Vitrectomy
System in more detail, Dr. Tornambe said that it may appear to be difficult to use,
but it is not. "The entry
is certainly much less traumatic than the older 25-g systems," he said. "I am convinced that the cannula system makes it much easier to get in and out than bare sclerotomies, and there is less trauma to the vitreous base. The sclerotomies are self-sealing and sutureless most of the time."
He pointed out that cannula insertion can be more difficult in subsequent surgeries because of scleral tunnel fibrosis, but the lack of bleeding and not having to open the conjunctiva for reoperations is "really a blessing." As a final tip on the Eckardt system, Dr. Tornambe addressed the challenge of trying to work at 12 o'clock through two oblique inferior incisions. "You can make one shelved incision directed inferiorly and the other directed superiorly," he said. "It really is not a big issue."
A VERSATILE APPROACH
Dr. Tornambe concluded by saying that surgeons can employ 23-g surgery in all cases except perhaps lens fragmentation. He expects, however, that future systems will be fully capable of handling those cases as well.