Superior versus Inferior Ahmed Glaucoma Valve Implantation

Purpose: To compare the efficacy and safety of Ahmed glaucoma valve (AGV) (New World Medical Inc., Rancho Cucamonga, CA) implantation in the superior versus inferior quadrants. Design: Prospective parallel cohort study. Participants: A total of 106 eyes of 106 patients with refractory glaucoma. Methods: Consecutive patients with refractory glaucoma underwent AGV implantation in the superior or inferior quadrants. Main Outcome Measures: Main outcome measures included intraocular pressure (IOP) and rate of complications. Other outcome measures included best corrected visual acuity (BCVA), number of glaucoma medications, and success rate (defined as at least 30% IOP reduction and 5<IOP <22 mmHg with or without medications). Criteria for failure included implant removal, additional glaucoma surgery, phthisis bulbi, or loss of light perception. Results: Of a total of 106 eyes, 58 and 48 eyes underwent AGV implantation in the superior and inferior quadrants, respectively. Baseline characteristics were comparable in the study groups, except for preoperative IOP, which was higher in the superior group (P = 0.01). Patients were followed for a mean period of 10.6 +/- 8.49 months and 10.58 +/- 6.75 months in the superior and inferior groups, respectively (P = 0.477). BCVA was comparable between the groups at all postoperative visits (P>0.122). After 1 year, statistically significant but comparable IOP reduction from baseline (P<0.001) was achieved in both groups (47.0% +/- 27.2% and 43.0% +/- 24.5% reduction for superior and inferior groups, respectively, P = 0.725). The mean number of glaucoma medications was comparable after 1 year (1.3 +/- 1.2 vs. 1.9 +/- 0.8 for superior and inferior implants, respectively, P = 0.256). Success rates were also similar at 1 year: 27 eyes (81.8%) versus 20 eyes (95.2%) for superior and inferior implants, respectively (P = 0.227). However, the overall rate of complications, such as implant exposure necessitating removal, cosmetically unappealing appearance, and endophthalmitis, was higher in the inferior group: 12 eyes (25%) versus 3 eyes (5.2%) for superior and inferior groups, respectively, (P = 0.004). Conclusions: Superior and inferior AGV implants have similar intermediate efficacy in terms of IOP reduction, decrease in number of glaucoma medications, and preservation of vision. However, the inferior quadrants entail significantly more complications. It may be prudent to avoid AGV implantation in the inferior quadrants if the superior quadrants have no contraindications to surgery. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. Ophthalmology 2009; 116:208-213 (C) 2009 by the American Academy of Ophthalmology.