Surgery

Small-gauge Retina Surgery: How Low Can You Go?

Understand the benefits and challenges of small-gauge surgery.

By Andrew E. Mathis, Ph.D., Medical Editor

Beginning in the 1970s, 20-gauge pars plana vitrectomy (PPV) became part of the standard of care in vitreoretinal surgery, employed to remove the vitreous in eyes suffering from a variety of conditions.

In 2002, surgeons at the Doheny Eye Institute at the University of Southern California reported their initial experience with 25-gauge vitrectomy, which was followed three years later by the introduction of 23-gauge vitrectomy by Claus Eckardt, MD, of the Municipal Eye Clinic in Frankfurt, Germany. These smaller-gauge systems have since largely replaced 20-g PPV.

What does the shift from 20-g to small-gauge vitrectomy mean for the allied health professional?

Understanding Small-gauge Retina Surgery

Generally, PPV involves the placing of two to four ports in the eye, which are placed via sclerotomies, or holes in the sclera created with trocars, into which thin tubes, called cannulas, are inserted. The instruments used to perform the actual vitrectomy are then introduced via the cannulas.

These instruments come in a fairly broad variety, including vitreous cutters, light pipes for endoillumination, and forceps, as well as infusion lines, through which replacement substances for the vitreous, called tamponades, can be inserted into the eye. Tamponades come in liquid, oil, and gas forms.

Among the advantages of small-gauge PPV is that sutures to close the sclerotomies are usually not required, as the wounds are so small that they will normally close on their own. Increasingly, surgical companies are developing small-gauge vitrectomy machines, which combine many of the technologies required during PPV, as well as lasers, tamponade agents, etc.

The Role of Ophthalmic Medical Personnel

Melinda Collier is an OR technician at the Wills Eye Institute in Philadelphia. For the last three years, she has been assisting in small-gauge PPV and has assisted in procedure using both 23- and 25-g PPV. “It really depends on the surgeon,” she says. “One of the surgeons with whom I work likes 25-gauge because the laser tip provides a little more leeway to maneuver within the eye.”

Ms. Collier’s experiences in the operating room have given her insight into how OMP s’ knowledge of small-gauge procedures can better prepare them for their roles in the OR.

For instance, many vitrectomy procedures are performed on patients with diabetes, who run particularly high risks of developing retinal complications. “Having a diabetic patient doesn’t change for the tech all that much,” Ms. Collier explains. “The procedure is pretty much the same, although there will be additional instruments. Laser is needed more often, and if there are lens fragments that have dropped to the back of the eye, you might want a fragmatome ready.”

Ms. Collier says that having a look at preoperative imaging can also be helpful to the OMP . She offers an entertaining example of how imaging can prepare her for assisting in treating a retinal detachment.

She says, “Imagine you were wearing a cape, like a superhero, and the wind was blowing it. If the retina looks like that, I know there’s going to be the need for things like perfluorocarbon [a gas used for tamponade]. These procedures will also take longer, so you plan accordingly.”

Challenges for Docs, Patients, and OMPs

Although small-gauge vitrectomy has, generally speaking, made the experience of vitreoretinal surgery easier for patients and healthcare professionals alike, it does come with some difficulties.

For instance, because of the sutureless approach, small-gauge surgery incurs some risks that larger-case instruments do not. Some surgeons have also complained that small-gauge surgical instruments, particularly 25-g instruments, are insufficiently rigid for delicate procedures; in fact, it was this complaint that gave rise, in part, to the relatively “medium-sized” 23-gauge system.

In addition, OMPs must be prepared to learn this new way of performing procedures, says Ms. Collier, who was trained at Wills to assist with Alcon’s Constellation vitrectomy machine.

“In the long run, using a machine like the Constellation is easier because there are no separate machines, and you have everything provided for you by one system,” she says. “However, it really is an adjustment to learn how the Constellation works. It’s very involved.” Once the machine is mastered, however, the OMP can be that much more effective an assistant during procedures.

On the Horizon

While 25-g vitrectomy is currently the smallest-gauge system available, even smaller systems are in development. The first reports on the use of 27-gauge vitrectomy, from Japan, began appearing five years ago. The surgical instrument producer Dutch Ophthalmic (Exeter, NH) is among the companies developing systems for use in the United States.

Because any instrument being inserted through a 25-g cannula must be narrower, some 27-g, and even 29-gauge, instruments are already in use, as well as illumination fibers as small as 30-gauge. It will be years before complete systems are available in the United States in such small sizes, but surgeons already using 25-g systems and finding them indispensable are likely to switch to even smaller gauges when they become available.

Thus, it behooves the surgical assistant to be prepared for those changes when they come. For those OMPs working in practices that have not already switched from 20-g systems to a smaller gauge, it is very likely such a change will be coming soon, given the proliferation of 23- and 25-g systems and instruments and the growing body of data on their use.

For Further Information

There are several publications on small-gauge vitrectomy readily available on the Web. For example, virtually every issue of Retinal Physician, a sister publication to Ophthalmic Professional, features an article on small-gauge vitreoretinal surgery. Also, the American Academy of Ophthalmology published a guide to small-gauge vitrectomy in the summer of 2010; you can consult it online at www.aao.org/publications/eyenet/201007/feature.cfm. OP