Article Date: 5/1/2006

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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.

Eckardt 23-g Vitrectomy System.

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