Complications Specifically Related to Trabectome® Surgery (Trabeculotomy Internal Approach)

Abstract

Current surgical therapy for open-angle glaucoma can be divided into procedures directed at decreasing aqueous inflow (such as cyclophotocoagulation) or increasing aqueous outflow. The latter group can be further subdivided into external filtering surgery (such as trabeculectomy and aqueous tube shunt implantation) and internal filtering surgery designed to enhance existing aqueous outflow pathways. Internal approaches provide an alternative to standard external filtering surgery and possibly reduce the complications, including hypotony, hypotony maculopathy, bleb leaks, blebitis, choroidal effusion and hemorrhage, bleb-related endophthalmitis, peripheral anterior synechiae (PAS) formation, posterior synechiae, cataract formation, diplopia, tube obstruction, conjunctival erosion, tube migration, corneal decompensation, and plate encapsulation. Anterior chamber angle surgery techniques include procedures performed by an internal approach (e.g., goniotomy, Trabectome® [NeoMedix Corporation, Tustin, California], trabecular stent [iStent®; Glaukos® Corp., Laguna Hills, California], excimer laser trabeculotomy) or by an external approach (e.g., canaloplasty [see Chapter 51] and viscocanalostomy). Trabeculotomy by internal approach with the Trabectome® is designed to create a direct pathway from the anterior chamber to Schlemm’s canal (SC) and the aqueous collector channels by using electrocautery to selectively ablate a portion of trabecular meshwork (TM) tissue and the inner wall of SC in order to increase aqueous outflow. The Trabectome® surgical device received FDA approval for clinical use in 2004. The system consists of 3 major components: a mobile stand with a gravity-fed bottle of balanced salt solution; a handpiece console with automated irrigation, aspiration, and microbipolar electrocautery; and a foot pedal to control these functions. The intraocular disposable handpiece (see Figure 50.1) tip contains a 19.5-gauge infusion sleeve and a 25-gauge irrigation and aspiration (I/A) port with a coupling for the ablation unit at the tip. The instrument incorporates a specially designed insulated triangular footplate that is bent at 90° at the end and is pointed in order to allow proper insertion through the TM into SC. The insulation on the footplate is made of a multilayered polymer coating that allows the instrument to glide along within the canal and protects the outer wall of SC from thermal and electrical injury.