23-gauge instruments have landed

"Conventional 20-gauge vitrectomy requires a 1.50 mm wide sclerotomy to be made and closed with sutures. To avoid the need for suture closure, the sclerotomy should not exceed 0.5 mm in width, which corresponds to 25-gauge instruments. If 23-gauge instruments are used, the sclerotomy must have a width of 0.72 mm. While this would normally require suture closure, it can be avoided by means of a tunnel incision that achieves self-sealing closure," Eckardt said.

He and his colleagues opt to use 23-gauge instrumentation because 25-gauge instruments, in his opinion, are generally too small for more complicated cases. "Even for macular surgery, 25-gauge instruments do not always offer an advantage. The smaller the forceps, for example, the longer it can take to remove a membrane."

When performing the vitrectomy, Eckardt explained that the sclerotomy should be made at an angle of about 30Þ to the sclera. The DORC inserter, which is a blunt instrument that has a spatula-like tip that merges with a cylindrical body holding a microcannula, allows easy insertion of the microcannulas into the scleral tunnel (Figure 2).

Available instruments

Numerous 23-gauge instruments are now available and include a pneumatic vitreous cutter; wide-angle endoillumination probe; flute needle; endodiathermy probe and endolaser probe; end-gripping forceps; vertical, straight, and curved scissors; and hem-stopper.

"Twenty-three gauge vitrectomy instruments are used to carry out the most complicated procedures, for example, a diabetic retinal detachment that requires a 180Þ peripheral retinectomy. Cases such as these are best treated with silicone oil tamponade; the use of 1,000 and even 5,000 centistoke silicone oil is not problematic. The silicone tube can be mounted on the microcannula," Eckardt said.

In practice

Within the past six months, Eckardt and colleagues have performed more than 400 cases using the 23-gauge instrument. The cases have ranged in difficulty from simple macular pucker to giant retinal tears. Today, he pointed out, the only cases for which he still uses 20-gauge instruments are those that require the removal of 5,000 centistoke silicone oil, removal of a foreign body, and removal of subretinal membranes that require angled instruments. No cases required placement of a suture at the end of the surgery, and none required conversion to 20-gauge technique. In addition, "we never injected air to tamponade the sclerotomy," he reported.

Complications have included the development of postoperative hypotony in 22 eyes that normalized after two days. Postoperative retinal detachments developed in three eyes, and endophthalmitis developed in two eyes.