Vitrectomy: Surgical Pearls
A discussion of the instruments and techniques used in vitrectomy surgery.
BY JACQUELINE ZUMMO, MEDICAL EDITOR

Vitrectomy prevents vision loss and makes possible the correction of some of the most complicated retinal diseases. The surgery consists of removing the vitreous gel through small incisions in the eye wall and replacing it with a special saline solution, which is similar to the liquid being removed from the eye. This article will compare the use of 20-gauge instruments to 25-gauge instruments, as well as discuss the many special techniques that are coupled with the surgery to achieve the desired results.

Philip Ferrone, M.D., of Long Island Vitreoretinal Consultants, N.Y., and Tarek Hassan, M.D., of Associated Retinal Consultants, Mich., discuss in detail their experience with 25-gauge vitrectomy.

VITRECTOMY INSTRUMENTS
20 gauge vs. 25 gauge

The first vitrectomies were performed using (19 and) 20-gauge instruments. These instruments require surgeons to make an opening through the conjunctiva, pushing it back and cauterizing under the incision to stop the bleeding. A 1-mm wound is then made in the sclera three times and the vitrectomy is performed. When the case is completed, one deep suture is used to close up each sclerotomy (totaling 3 deep sutures), and four to six sutures are required to close the conjunctiva. Though the sutures dissolve quickly, initially they are stiff, which causes tearing and discomfort to the eye. The deep sutures used in a 20-gauge sclerotomy also have a tendency to induce an astigmatism that may last up to 3 months.

In 2001, Bausch & Lomb (B&L, Rochester, N.Y.) in conjunction with Eugene de Juan, M.D., developed a 25-gauge instrument for vitrectomy. Because the 25-gauge instrument is substantially smaller, only 0.5 mm compared to the 1-mm 20-gauge instrument, there is no significant disruption of the conjunctiva. This minimal disruption of the external tissues allows surgeons to enter the eye with small incisions using a cannula system that does not require sutures because the incision is only 0.5 mm. Though 25-gauge vitrectomy is considered as invasive as a 20-gauge procedure, it allows for smaller incisions to be made.

"With 25-gauge vitrectomy, you can treat most things that you can with 20 gauge, but patient recovery is much faster with the 25-gauge cases. This leads to the same beneficial result with surgery; however, the patients can usually get back on their feet and back to their usual routine faster," says Dr. Ferrone.

According to Dr. Ferrone, the following instruments are helpful for use with 25-gauge vitrectomy:

Photon light (Synergetics Inc., St. Charles, Mo.). Excellent light source for use in 25-gauge vitrectomy, because it is very bright and only uses a 200-μm fiber in each light probe, which leads to being able to develop multifunction instruments and allows for a more rigid light probe with a thicker shaft.

Vitrector (B&L). This 25-gauge cutter has the best flow at a high cut rate. The only minor drawback is that it is a little bigger and heavier than the present pneumatic cutters. Presently this trade off is acceptable because it does have the best fluidics of the 25-gauge cutters.

Entry System (B&L). Second-generation trocar-cannula system is best because it enters the eye easily and has the best wound architecture for self-sealing. The wound made with this system heals well.

Tano Diamond Dusted Membrane Scrapper (Synergetics Inc.). This instrument allows the surgeon to peel membranes or internal limiting membranes easily.

Pic Forceps (B&L and Synergetics Inc). They work well for dealing with any macular pathology or epiretinal membrane. The pic forceps grasp well and tend not to lose their function, even with some tissue in them. One difference between the two companies is that the Synergetics' pic is sharper, which may be helpful in some situations.

Illuminated Irrigating Cannula (Synergetics Inc). With this instrument, fluid comes in from the cannula where a light fiber acts like a chandelier. No separate port is needed for the entry of the chandelier because it goes in with the infusion line port. It also does not torque on the eye, and the flow from the cannula is not impeded by the fiber optic. This instrument also has little to no risk of ocular light toxicity, and you can free up the hand that would usually hold the light pipe when using this instrument.

Special Techniques

With 25-gauge surgery, the following can be used as an adjunct to cases:

• intraocular gases — SF6 gas

• scleral buckling

• endophotocoagulation — green laser

• silicone oil — can be used with 25-gauge vitrectomy, but a larger sclerotomy may have to be made to instill the oil and this may require a suture.

Dr. Ferrone says, "Most surgeons believe that if you are doing a case that is bad enough for silicone oil to be considered, they will feel more comfortable manipulating that pathology with 20-gauge instrumentation."

Treatable Disorders with 25-gauge Instrumentation

Though the 25-gauge vitrectomy is ideal for certain retinal disorders, including macular holes, macular puckers, moderate proliferative diabetic retinopathy and retinal detachments, "It cannot be used to treat very complicated peripheral pathologies with complicated proliferative vitreoretinopathy," says Dr. Hassan s. "For these diseases, 20-gauge vitrectomy must still be used."

Dr. Ferrone adds that "you can correct most retinal diseases with 25 gauge, but at this point, I wouldn't throw away my 20-gauge instrumentation." Out of Dr. Ferrone's nine- member practice, most of his group uses 25-gauge instrumentation.

Time for Surgeons

Though 25-gauge instrumentation may not decrease the time involved in performing a vitrectomy, it does shift the amount of time spent from the opening and closing of wounds to working inside the eye.

Dr. Ferrone explains that, "going in to make the ports, which are the entries into the eye, is definitely quicker with 25 gauge. This is because you don't have to deal with controlling the conjunctival and episcleral bleeding, and you don't have to sew in the infusion line. However, the vitrectomy itself takes longer."

The procedures requires more time because the tube that is used to remove the vitreous is smaller with 25-gauge instrumentation and does not grasp the vitreous as quickly as the 20-gauge vitrector. Dr. Ferrone adds, "Another factor that can contribute to the increased vitrectomy time is that the technical manipulation of the 25-gauge instrumentation is tougher." Overall, the time for the complete procedure could be the same or even a little longer initially, but the surgery goes faster with experience.

Postoperative Care and Patient Comfort

With 25-gauge vitrectomy, the recovery time for the patient is shortened dramatically. First, patients see better the next day postoperative. Second, instead of being on drops for several weeks as would be the case with 20 gauge, patients are only on drops for 1 week, or 2 weeks maximum. The drops are not necessary after this 2-week time frame because with 25-gauge surgery, the healing is nearly complete.

Dr. Ferrone says that "the beauty of 25 gauge is that the next day it is difficult to tell which eye had surgery. The patient feels fine and is extremely comfortable, in contrast to how they usually feel after 20-gauge surgery. The biggest complaint the first day after 25g surgery is, 'I thought my vision would improve more,' as opposed to 'my eye is uncomfortable.'" He adds, "The issues discussed the day after surgery reflect just how great this technical advance is."

Patients with macular holes who would be face down and have irritation for 2 weeks after 20-gauge surgery only need to be face down for about 5 days with 25-gauge techniques, and they feel more comfortable. After those 5 days, patients are back to normal, resuming their everyday functions. "I have a patient who had one eye done the 20-gauge way, and the other eye done by me (25 gauge). The patient can't believe how much easier the recovery was after the 25-gauge vitrectomy," notes Dr. Ferrone.

Overall, 25-gauge vitrectomy has become increasingly important for performing vitreous surgery. "The techniques and the instrumentation have evolved dramatically since the onset," says Dr. Hassan.

Dr. Ferrone adds, "with 20 gauge, there is more tissue disruption and that translates into what patients feel and how quickly they recover. In many cases, 25-gauge vitrectomy is a great thing to do."