feature
A
Third Option in the Gauge Debate
Some
surgeons believe 23-g vitrectomy offers the best of both worlds.
FRANK CELIA, CONTRIBUTING
EDITOR
As the debate
continues regarding the merits of conventional 20-g vitrectomy surgery vs the newer
25-g vitrectomy, a third option is quietly gaining ground: 23-g sutureless transconjunctival
pars plana vitrectomy. Twenty-three gauge surgery represents a middle-of-the road
compromise, avoiding many of the drawbacks associated with the smaller-gauge surgery
while still delivering the benefits of a minimally invasive technique, surgeons
say.
Currently, Dutch Ophthalmics Research Center (DORC, Zuidland,
The Netherlands) is the only company offering a complete 23-g vitrectomy system
(Eckardt Vitrectomy System), although some other manufacturers do offer 23-g instruments
and accessories.
"I am converting all my cases to 23-g," says Paul E. Tornambe,
MD, of Poway, Calif, and a consultant for DORC. "I think this is the future for
this kind of surgery." Other companies are planning to unveil 23-g systems in the
near future, he says, adding that Alcon is expected to introduce its system at the
American Academy of Ophthalmology meeting later this year. The only situation for
which 23-g is not suited is a pars plana lensectomy, he says, but otherwise it can
accomplish everything a 20-g surgery can, only in a more efficient and safe manner.
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Eckardt 23-g
Vitrectomy System.
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LESS TRAUMA, SMALLER LEARNING
CURVE
If a 23-g sclerotomy is not manipulated,
the wound is self sealing. Dr. Tornambe favors the Eckardt cannula system. "When
I first saw the cannula system, I thought it was going to be cumbersome and difficult,
but it is simple. It is much less traumatic in my hands than the 25-g entry where
you have the lip of the wound to get around and get the instrument in," he says.
The 23-g infusion cannula can be used during 20-g surgery without
significant modifications by the surgeon. There is approximately a one-third reduction
in the number of cases that require suturing after the instruments are removed.
When using the 23-g infusion cannula in such cases, the surgeon should maintain
a higher-than-normal pressure, approximately 35 mm Hg to 40 mm Hg, to keep up with
the 20-g cutter and to avoid hypotony, says Dr. Tornambe.
One
major advantage cited by surgeons is the lack of learning curve in switching from
20-g to 23-g. The jump from 20-g to 25-g requires a great deal more skill and patience,
mainly because the 25-g instruments are more flexible than the 20-g. Twenty-three
gauge instruments retain the sturdiness of their 20-g counterparts, surgeons say.
"Twenty-five gauge vitrectors are a little too flexible in my opinion," says Richard
Spaide, MD, of New York City. "If you are working in the back of the eye, it is
not that big a deal, but once you start working near the front of the eye, it is
easier on the physician when you have an instrument that is less flexible."
Also, 23-g technology allows for transconjunctival-transscleral
incisions. "I don't open the conjunctiva anymore, even with 20-g cases," says Dr.
Tornambe.
Finally, some surgeons consider the smaller port and slower flow
rate safer when operating on a detached retina because of the decreased risk of
snagging retinal tissue.
ENDOILLUMINATION CONCERNS
With the advent of newer, stronger light
sources, comprehensive endoillumination is not as big a concern in small-gauge surgery
as it once was. However, there are some advantages to be gained by 23-g surgery
over 25-g. The wider diameter of the 23-g instruments allows for a more nuanced
design of the fiber optic tip of hand-held light sources, notes Dr. Spaide, 1 of
the developers of the 23-g TotalView Endoillumination (DORC). This makes for light
sources that can combine focused and diffused light in more efficient light patterns
than smaller instruments, he says.
Even with improved filtering systems, today's stronger light sources
also raise concerns about phototoxicity, especially in cases involving indocyanine
green (ICG) dye. When phototoxicity is a concern, diffuse light produced by chandeliers
such as the Tornambe Torpedo minilight (Insight Instruments, Inc., Stuart, Fla)
and the Neptune chandelier (DORC) are much safer than endoillumination probes. The
chandeliers are easy to insert and are a popular option for complex, bimanual surgeries.
But for certain procedures, a focused light source is still preferred.
Dr. Tornambe points out that 1 of the limitations of chandelier light is its lack
of ability to illuminate the vitreous base very well. Also, chandelier light produces
fewer reflections, and reflections can be important visual cues. "If you are used
to peeling membranes by getting your cues from light reflected off the retina, you
won't get that with a chandelier," he notes.
Dr. Tornambe is proponent of ICG dye, but cautions that when using
a focused light source to make sure it stays a safe distance from the retina. "My
feeling is if you use only 1 mg/ml [of ICG solution] and you infuse it and remove
it immediately, and you are careful with the focused light source, you should not
have problems." When operating close to the macula with a focused light, he times
his procedures to make sure they stay within a 10- to 15-minute range.
CHANGES AHEAD
Whether 23-g surgery bests 25-g surgery
in the judgment of retinal surgeons remains to be seen. But once small-gauge surgery
systems become more readily available, many surgeons may agree with Dr. Tornambe's
conclusion: "There is no question in my mind that 23-g surgery is going to replace
20-g."
Retinal Physician, Issue: May 2006