TRANSCONJUNCTIVAL SUTURELESS 23-GAUGE VITRECTOMY

Abstract

One of the most innovative vitreoretinal surgery techniques introduced in recent years is transconjunctival sutureless vitrectomy developed by Fujii et al.1,2 In this procedure, three polyamide microcannulas are inserted transconjunctivally through the sclera in the area of the pars plana. The vitreoretinal instruments and infusion line are then introduced through these cannulas into the vitreous cavity. Because a thin 25-gauge instrumentarium is used, the incisions left in the sclera after removal of the cannulas are so small that they self-seal without suturing. The procedure has quickly found many advocates. It causes no surgical trauma to the conjunctiva, requires no scleral suture (and thus leaves no postoperative suture-related astigmatism), and entails a distinctly reduced rehabilitation time. Many vitreoretinal surgeons, however, reject the method at all or accept it only for special indications. One of the most frequent objections is that the 25-gauge instruments are too flexible for many of the complicated tasks performed on the retina and vitreous body. A method for transconjunctival sutureless vitrectomy using a 23-gauge instrumentarium that overcomes this flaw is presented. As in transconjunctival sutureless 25-gauge vitrectomy, 3 microcannulas for the instruments and infusion line are inserted transconjunctivally into the area of the planned sclerotomy. The incisions are not made perpendicular to the scleral surface (i.e., toward the posterior pole) but at a 30° to 40° angle parallel to the corneoscleral limbus (Fig. 1). The tunnel-like nature of these incisions facilitates the self-sealing of the wound after removal of the cannulas. The procedure is started by pushing the conjunctiva 1 mm to 2 mm laterally (i.e., parallel to the corneal limbus) in the inferotemporal, superotemporal, and superonasal quadrants using a special pressure plate (DORC, Zuidland, Holland) to hold it firmly to the sclera (Fig. 2). A 23-gauge stiletto blade (45° angle; BD Medical–Ophthalmic Systems, Franklin Lakes, NJ) is then inserted at a 30° to 40° angle through the conjunctiva, sclera, and pars plana 3.5 mm from the corneoscleral limbus (Fig. 3). To obtain scleral tunnels parallel to the corneoscleral limbus, the scleral incisions are made radial to the corneoscleral limbus (Fig. 1). The incision with the 23-gauge stiletto blade is 0.72 mm wide. Constant pressure is applied to the pressure plate while the incision is made and during withdrawal of the stiletto blade to prevent slippage of the conjunctiva against the sclera. Should displacement occur, it would be difficult if not impossible to subsequently locate the incision in the conjunctiva and sclera. The microcannula is then inserted through the conjunctival incision and into the scleral tunnel using a specially designed blunt inserter (DORC). The microcannula and the inserter are both made of steel. The length of the cannula (without its head) is 4 mm, the internal diameter of the cannula is 0.65 mm, and the external diameter is 0.75 mm. The inserter is not a beveled trocar but a blunt instrument whose spatula-like tip merges with a cylindrical body holding the microcannula (Fig. 4). The external openings of two of the three cannulas are funnel shaped (Figs. 5 and 6) to facilitate insertion of the instruments.