Downloaded from http://journals.lww.com/glaucomajournal by BhDMf5ePHKbH4TTImqenVDZHALwmCBBpXdU/M24fbsEkFikwqPa/bBkAEKChwpGfSToKNQtxZC0= on 12/10/2019 Outcomes and Complications of Ahmed Tube Implantation in Asian Eyes Jessica Q.H. Choo, MBBS,* Z.D. Chen, MBBS,* Victor Koh, MMed (Ophthalmology),* Shen Liang, PhD,† Cecilia M. Aquino, MMed (Ophthalmology),* Chelvin Sng, MRCSEd (Ophthalmology),* and Paul Chew, FRCSEd (Ophthalmology)* Purpose: There is a lack of long-term Asian studies on the efficacy and safety of Ahmed glaucoma valve (AGV) implantation. This study seeks to determine the outcomes and complications of AGV implantation in Asians. Methods: A retrospective review of AGV surgeries performed at a single center in Singapore was conducted. A total of 76 patients with primary and secondary glaucoma who underwent their first AGV surgery from January 1, 2010 to December 31, 2012 were consid- ered for our study. Primary outcomes evaluated were as follows: failure, intraocular pressure, best-corrected visual acuity, number of intraocular pressure (IOP)-lowering medications, and complica- tions. Failure was defined by the following: IOP > 21 mm Hg on 2 consecutive visits after 3 months, IOP ≤ 5 mm Hg on 2 consecutive visits after 3 months, reoperation for glaucoma, removal of implant, or loss of light perception vision. Results: Mean follow-up duration was 33.2 ± 6.9 months. There was significant reduction in IOP (mean reduction, 25.9%; P < 0.001) and number of IOP-lowering medications (mean reduction, 77.8%; P < 0.001) at 3 years. Absolute failure rate was 23.9% at 3 years with no difference between eyes with or without previous trabeculectomy and between eyes with primary or secondary glaucoma. Occurrence of postoperative hyphema was a significant risk factor for failure. The commonest postoperative complications were hyphema and tube exposure. Conclusions: At 3 years after AGV surgery in Asian eyes, less than one-quarter of the eyes fulfilled the criteria for surgical failure. Key Words: glaucoma, tube shunts, glaucoma drainage devices, Ahmed glaucoma valve, trabeculectomy (J Glaucoma 2018;27:733–738) G laucoma is the leading cause of irreversible blindness globally, which is expected to affect up to 111 million people worldwide by 2040, and Asians accounting for ~60% of these cases. 1 In Singapore, about 4% of the population have glaucoma, in which 1.7%, 1.5%, and 0.8% of the population have primary open-angle glaucoma (POAG), primary angle-closure glaucoma (PACG), and secondary glaucoma, respectively. 2 Glaucoma drainage devices are traditionally used in the management of refractory glaucoma, which fails to respond to medical treatment, laser procedures, and filtra- tion surgery. 3 The 5-year outcomes of the Tube versus Trabeculectomy trial comparing repeat trabeculectomy and Baerveldt tubes in eyes with failed trabeculectomy showed that the latter had higher success rates. 4 Indeed, there has been a shift away from trabeculectomy and an increase in popularity of glaucoma drainage implant surgery. 5 Com- pared with Baerveldt tubes, the pooled analysis of Ahmed Baerveldt Comparison Study and the Ahmed Versus Baer- veldt Study showed that Ahmed glaucoma valve (AGV) implants had a higher failure rate and reoperation for glaucoma but associated with a lower risk of hypotony at 5 years. 6 Nevertheless, longer term studies on the efficacy and safety of both primary and secondary AGV implanta- tion among Asian eyes are lacking. To address this gap, we conducted a retrospective 3-year follow-up study with the aim to determine the out- comes and complications of AGV implantation in an Asian population. METHODS This was a retrospective review of 120 consecutive eyes of patients who underwent AGV (New World Medical Inc., CA) surgery at National University Hospital in Singapore between January 1, 2010 and December 31, 2012. The inclusion criteria for our study were as follows:  18 to 85 years of age.  Diagnosed with glaucoma.  ≥ 3 intraocular pressure (IOP) recorded before operation, measured on separate visits.  No previous glaucoma drainage tube implantation before the study period. We excluded the second eye of patients who underwent glaucoma drainage tube implantation in bilateral eyes, as per the methodology used by similar studies previously. 7 The study was conducted in accordance with the tenets of the Declaration of Helsinki and had ethics approval from the National Healthcare Group Domain Specific Review Board. Glaucoma is defined as the presence of characteristic optic disc changes (thinning, excavation, or focal notch of the neurosensory rim, or asymmetrical cupping between the eyes of > 0.2) and IOP ≥ 21 mm Hg on ≥ 1 visits pre- operatively by Goldman applanation tonometry with Received for publication February 11, 2018; accepted June 8, 2018. From the Departments of *Ophthalmology; and †Biostatistics, National University Health System, Singapore, Singapore. Disclosure: The authors declare no conflict of interest. Reprints: Victor Koh, MMed (Ophthalmology), Department of Oph- thalmology, National University Health System, 1E Kent Ridge Road, Level 7, NUHS Tower Block, Singapore 119228, Singapore (e-mail: victor_koh@nuhs.edu.sg). Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000001004 ORIGINAL STUDY J Glaucoma  Volume 27, Number 8, August 2018 www.glaucomajournal.com | 733 Copyright r 2018 Wolters Kluwer Health, Inc. All rights reserved.