Occlusive ligature and standardized fenestration of a Baerveldt tube with and without antimetabolites for early postoperative intraocular pressure control

Objective: To determine the effectiveness of a surgical modification for a nonvalved aqueous tube shunt in controlling intraocular pressure (IOP) in t he early postoperative period. The effect of antimetabolite use on IOP also was studied. Design: A retrospective study of consecutive patients who underwent modifie d Baerveldt 350-mm(2) implant with varied, nonrandomized, exposure to antim etabolites. Participants: Fifty-one eyes of 46 patients with uncontrolled glaucoma were examined. Intervention: Identical surgical modification of a Baerveldt 350-mm(2) tube was performed in all cases and consisted of placement of an occlusive 7-0 polyglactin suture just anterior to the plate followed by a through-and-thr ough penetration of the tube just anterior to the occlusive ligature with a standardized 15 degrees blade. Seventeen eyes were not exposed to antimeta bolite, while 2 groups of 17 eyes had 3 minutes' episcleral exposure to eit her 5-fluorouracil 50 mg/ml or mitomycin C 0.4 mg/ml at the location corres ponding to the fenestration. The Tenon's layer and conjunctiva were not exp osed because of concerns regarding conjunctival erosion over the device. Main Outcome Measure: Intraocular pressure and number of antiglaucoma medic ations required were analyzed. Results: For the group, mean IOP before surgery and on postoperative days 1 , 4, 10, 21, 42, 63, 84, and 112 was (in millimeters of mercury) 34.6, 20.1 , 17.0, 17.2, 22.0, 17.3, 18.7, 17.4, and 15.6, respectively. There was an elevation of IOP at day 21 relative to fibrotic blockage of the fenestratio n before suture autolysis. This was temporized with antiglaucoma medication until suture autolysis occurred or treated with laser suture lysis (8 eyes ). On day 1, hypotony occurred in 3 (6%) eyes whereas IOP greater than 30 m mHg was observed in 13 (26%) eyes. By day 10, the frequency had decreased t o one (2.1%) eye and three (6.4%) eyes, respectively. The use of antimetabo lites did not result in lower IOP or less medication needed for any group a t any interval (analysis of variance). Conclusion: This modification of a nonvalved glaucoma tube shunt device pro vides adequate IOP control in the early postoperative period with a low rat e of hypotony and surgical complications. If elevation of IOP occurs before suture autolysis, it generally is well controlled by antiglaucoma medicati ons or laser suture lysis. Antimetabolite exposure did not influence early postoperative IOP in this study.