Intermediate-term Outcome and Success of Superior Versus Inferior Ahmed Glaucoma Valve Implantation

Purpose: The superotemporal quadrant is usually the implantation site of choice for glaucoma drainage devices. Inferior placement of glaucoma drainage device is considered technically difficult. The purpose was to determine the success rates, complications, and visual outcome of superior versus inferior Ahmed Glaucoma Valve implantation. Patients and Methods: A retrospective review of the records of 83 eyes (77 patients) that underwent Ahmed Glaucoma Valve surgery from 1997 to 2004. Thirty-one eyes had Superior insertion (SI) versus 52 eyes with inferior insertion (II). Demographic, preoperative, and postoperative data including intraocular pressure (IOP), visual acuity, and number of medications, and complications were recorded. Success was defined as postoperative IOP between 5 and 21 mm HP and at least a 20%, reduction from baseline IOP. Results: The mean postoperative IOPs at 6 months, 1, 2, 2.5, and 3 years were 13.5 +/- 3.2 mm Hg versus 12.8 +/- 3.6 mm Hg (P = 0.76), 12.5 +/- 3.1 mm Hg versus 13.0 +/- 4.0 mm Hg (P = 0.5), 15.7 +/- 6.2 mm Hg versus 12.6 +/- 4.7 mm Hg (P = 0.06), 13.2 +/- 3.0 mm Hg versus 12.6 +/- 3.3 mm Hg (P = 0.70), and 14.5 +/- 3.0 mm Hg versus 13.7 +/- 5.0 mm Hg (P = 0.73) in the SI group versus the II group, respectively. The success rates were similar between the groups over the study period with 87.0% versus 86.5%, 71.5%, versus 73%, and 71.5% versus 64.61% for SI versus II at 12, 24, and 36 months, respectively. There were more complications in the II group; however, only wound dehiscence and transient diplopia were statistically significant (P = 0.04 and 0.001, respectively). The number of glaucoma medications was lower in the SI during the first 3 months but nonsignificant thereafter. Conclusions: There was no significant difference in IOP control between SI and II over 36 months. II Should be considered when there are limitations to SI.