The protective scleral flap over a limbal fistula, which reduces the chances of an early postoperative flat anterior chamber, makes the guarded filtering operation particularly desirable for combined procedures. Several techniques were described for combining a trabeculectomy with intracapsular cataract surgery during the 1970s (103,104,105), but it was not until the popularity of extracapsular cataract extraction and PC IOL implantation (the “triple procedureâ€) in the 1980s (106,107,108,109) and phacoemulsification in the 1990s, that combined trabeculectomy and cataract extraction began to provide reasonably consistent long-term glaucoma control.
Phacoemulsification has become the preferred cataract technique for combined procedures during the 1990s and appears to be associated with further improvement in the long-term success rates. The procedure can be combined with a trabeculectomy by utilizing the fistula for the cataract incision (110). The incision may be 6 mm to insert a rigid IOL, or less than 3 mm for a foldable lens. The latter has been shown to have a significantly lower incidence of postoperative complications and better visual acuity in the early postoperative period (111). After creating a superior scleral tunnel and converting the tunnel to a scleral flap, a limbal fistula is created under it (single-site technique). If a scleral tunnel incision is used, the fistula can be excised from the posterior lip of the incision, leaving the anterior lip of the tunnel to cover the fistula (112) (Fig. 44.3).
One of the commonly used techniques is to perform a phacoemulsification through a separate temporal corneal incision as a first step, followed by a trabeculectomy at the superior limbus (two-site technique) (101,113,114). Prospective studies, comparing single-site versus two-site approaches, have shown that patients in the two-site group had 1 to 2 mm Hg more IOP reduction and required less postoperative medications (115,116,117), although the differences were not statistically significant.
An alternative approach with ECCE involves preparation of the partial-thickness scleral flap and limbal fistula in the usual manner, followed by extension of the corneoscleral incision from either side of the fistula. After a standard ECCE and implantation of the PC IOL, both scleral flap and corneoscleral or corneal incision are closed with multiple sutures. The conjunctival flap is closed in the manner described for glaucoma filtering procedures (see Chapter 40). A limbal based versus fornix-based conjunctival flap was found to have no difference on the outcome of trabeculectomy combined with either ECCE (118,119) or phacoemulsification and PC IOL (120,121,122,123,124). The use of topical apraclonidine 1% before, immediately after, and 12 hours after surgery was shown to provide better IOP control after combined ECCE and trabeculectomy (125), although using apraclonidine 1% once after phacoemulsification has not demonstrated significant IOP reduction (126). Oral acetazolamide (127) and topical dorzolamide (128) have been shown to be more effective in controlling postoperative IOP elevation than apraclonidine.
Several studies have compared phacoemulsification to ECCE in combination with a guarded filtering procedure, with the general results that the former is associated with fewer complications, improved long-term IOP control, and a better visual outcome (52,112,129).
