The Effect of Tube Ligature on the Safety and Efficacy of Ahmed Glaucoma Valve Surgery

Precis: In this matched case-control study, ligature of the Ahmed glaucoma valve (AGV) was associated with a reduction in the rate of postoperative complications without affecting the surgical success rate or the visual outcome following the procedure. Purpose: The purpose of this study was to compare the safety and efficacy of AGV surgery with and without tube ligation. Materials and Methods: This was a retrospective, matched case-control study. A review was performed of patients who underwent AGV surgery with tube ligation between June 2015 and December 2017 (ligated AGV group). Cases were matched with controls who underwent AGV surgery without tube ligation (nonligated AGV group). Data were compared on postoperative intraocular pressure (IOP), the number of glaucoma medications, surgical success rates, complications, and vision. Results: There were 49 eyes in the ligated AGV group, and 98 eyes in the nonligated AGV group. Baseline characteristics were similar between groups except for the number of glaucoma medications (3.72 +/- 0.55 in the ligated AGV group vs. 3.92 +/- 0.92 in the nonligated AGV group; P<0.01). At 18 months, IOP was 16.7 +/- 6.3 mm Hg in the ligated AGV group and 17.3 +/- 8.0 mm Hg in the nonligated AGV group (P=0.76). In addition, the mean number of glaucoma medications was 2.38 +/- 1.10 in the ligated AGV group and 1.68 +/- 1.51 in the nonligated AGV group (P=0.56). The overall success rate at 12 months was similar between groups (P=0.84). The overall rate of complications was statistically lower in the ligated AGV group (28.6%) compared with the nonligated AGV group (73.5%) (P<0.01). The mean change in logarithm of the minimum angle of resolution acuity was similar between groups (P=0.50). Conclusion: Tube ligation in AGV surgery may be an effective measure that reduces the rate of postoperative complications without affecting the success rate or visual outcomes of the surgery.