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Year : 2016  |  Volume : 23  |  Issue : 1  |  Page : 104-109  

Long-term outcomes of ahmed glaucoma valve implantation in refractory glaucoma at Farabi Eye Hospital, Tehran, Iran

1 Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
2 Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
3 Department of Health Sciences, California State University, Northridge and Translational Pathology Core Laboratory, University of California, Los Angeles, USA

Date of Web Publication4-Jan-2016

Correspondence Address:
Ramin Daneshvar
Khatam Anbia Eye Hospital, Ghareni Blvd, Mashhad 91959-61151
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0974-9233.164611

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Purpose: To describe long-term outcomes and complications of Ahmed glaucoma valve (AGV) implantation in subjects with refractory glaucoma at Farabi Eye Hospital, Tehran, Iran.
Materials and Methods: This retrospective cohort study evaluated patient records of all subjects with refractory glaucoma who had undergone AGV implantation up to January 2013. The main outcome measure was the surgical success rate. Complete success was defined as intraocular pressure (IOP) <22 mmHg, without anti-glaucoma medications or additional surgery. Qualified success was IOP <22 mmHg regardless of number of anti-glaucoma medications. In all cases, loss of vision (no light perception) was considered an independent indicator of failure. Data were also collected on intraoperative and postoperative complications.
Results: Twenty-eight eyes were included in the study. With a mean follow-up of 48.2 ± 31.7 months (median: 40.50 months; range: 3–124 months), the IOP decreased from a mean preoperative value of 30.8 ± 5.6 mmHg to 20.0 ± 6.4 mmHg at last visit. The number of medications decreased from 3.7 ± 0.4 preoperatively to 2.5 ± 1.1 postoperatively. Cumulative qualified success was achieved in 69% of eyes. Mean time to failure according to qualified success criteria was 92.3 ± 9.4 months. Postoperative complications were recorded in 16 (57.1%) eyes. The most common complication was focal endothelial corneal decompensation at the site of tube-cornea touch.
Conclusion: AGV implantation with adjunctive topical anti-glaucoma drops controlled IOP in approximately 70% of eyes with refractory glaucoma with a median of 40.5 months of follow-up. However, complication rates were higher.

Keywords: Ahmed Glaucoma Valve, Glaucoma Drainage Implant, Intraocular Pressure, Refractory Glaucoma

How to cite this article:
Zarei R, Amini H, Daneshvar R, Nabi FN, Moghimi S, Fakhraee G, Eslami Y, Mohammadi M, Amini N. Long-term outcomes of ahmed glaucoma valve implantation in refractory glaucoma at Farabi Eye Hospital, Tehran, Iran. Middle East Afr J Ophthalmol 2016;23:104-9

How to cite this URL:
Zarei R, Amini H, Daneshvar R, Nabi FN, Moghimi S, Fakhraee G, Eslami Y, Mohammadi M, Amini N. Long-term outcomes of ahmed glaucoma valve implantation in refractory glaucoma at Farabi Eye Hospital, Tehran, Iran. Middle East Afr J Ophthalmol [serial online] 2016 [cited 2022 Aug 19];23:104-9. Available from: http://www.meajo.org/text.asp?2016/23/1/104/164611

   Introduction Top

Globally, glaucoma is the leading cause of irreversible blindness, and this is especially relevant to complicated, refractory cases of glaucoma.[1] Glaucoma drainage devices (GDD) are frequently used for the management of refractory glaucoma cases, and as a secondary choice following failure of other surgeries. Additionally, several studies have reported favorable results with GDD implantation as the primary surgical option in glaucoma patients.[2],[3],[4]

The Ahmed glaucoma valve (AGV; New World Medical, Inc., Rancho Cucamonga, California, USA) was introduced into the market at 1993 and has a built-in silicone venturi valve to restrict aqueous outflow and prevent postoperative hypotony.[5] It is used in refractory glaucoma cases both as a primary surgical choice and after the failure of conventional filtering surgery.

Several reports exist on success rate of AGV in different situations and races.[4],[6],[7],[8],[9] However, reports are rare on long-term outcomes of the device from the Middle East. In the current study, we evaluated the outcomes of AGV implantation in refractory glaucoma cases in a major Tertiary Eye Hospital in Iran.

   Materials and Methods Top

This retrospective cohort study evaluated the medical records of patients with refractory glaucoma who underwent AGV implantation at Farabi Eye Hospital, Tehran, Iran. The chart review included all consecutive cases with refractory glaucoma, unresponsive to medical and conventional surgical intervention, who underwent AGV implantation by one surgeon (Prof. Heidar Amini) between July 2002 and April 2004. We selected this period to evaluate the long-term result of the cases that is the fate of the procedure over a 10-year period. The chart review was performed in 2013. Patients with previous drainage device implantation were excluded from the study. As the hospital serves both primary and referral patients, some of the operated patients are followed-up by the referring physician and have follow-up data were missing after the 1st postoperative week. These cases were excluded from this study. Preoperative data were collected on patient age, gender, intraocular pressure (IOP) measured by a calibrated Goldmann applanation tonometer, number of anti-glaucoma medications, best-corrected visual acuity using a tumbling E-chart, and cup-to-disk ratio. Surgical data were collected including any intraoperative complications along with other intraoperative findings and site of AGV implantation. Postoperatively, data were collected on IOP, the number of medications and complications. All surgical and clinic records in the hospital were hard copies and were reviewed case by case for this study.

Complete success was defined as IOP <22 mmHg, without anti-glaucoma medications or need for additional surgery. IOP <22 mmHg regardless of the number of anti-glaucoma medications was classified as qualified success. IOP ≥22 mmHg with maximal, tolerable medications, IOP ≤5 mmHg, need for additional surgical intervention, loss of light perception, or phthisis bulbi was considered a surgical failure.

Surgical technique

One experienced surgeon (HA) performed all surgeries. Briefly, under monitored anesthetic care along with topical and subconjunctival anesthesia for adult patients and general anesthesia for pediatric subjects; a clear corneal traction suture was placed parallel to limbus and a limbal based superotemporal or superonasal peritomy was performed. The AGV was primed with balanced salt solution, and its plate was fixed to sclera at least 10 mm posterior to the surgical limbus with two nylon 8-0 sutures. The tube was trimmed and inserted into the anterior chamber in a plane parallel to iris and as far from corneal endothelium as possible. A scleral patch graft from banked donor sclera was placed over the tube, and water tight closure of Tenon's and conjunctiva was performed with running vicryl 8-0 sutures. At the conclusion of surgery, subconjunctival cefazoline, and betamethasone were administered.

Statistical analysis

The main outcome measure was surgical success rate. Kaplan-Meier survival analysis was performed to evaluate success rate over the study period. Furthermore, repeated measure analysis of variance (ANOVA) along with Bonferroni adjustment was performed to evaluate IOP and medication changes over time. All statistical analyses were performed using SPSS software (IBM Corp., New York, NY, USA). A P < 0.05 was considered as statistically significant.

   Results Top

Twenty-eight eyes of 28 patients were eligible and included. The mean age was 44.3 ± 22.3 years (median: 44.00 years; range: 7–75 years). Fifteen patients were male (53.5%), and all included patients were Caucasians and Iranians. The mean follow-up time was 48.2 ± 31.7 months (median: 40.5; range: 3–124 months); 92.8% had at least 12 months follow-up and 78.5% of participants had 24 months follow-up. Pseudophakic glaucoma was the most common type of glaucoma (13 eyes; 46.4%). Demographic and preoperative clinical data of the participants are summarized in [Table 1].
Table 1: Demographic data and preoperative characteristics of eyes that underwent Ahmed glaucoma valve implantation in this study

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Mean preoperative IOP was 30.8 ± 5.6 mmHg (range: 23.0–50.0 mmHg) with 3.7 ± 0.4 medications (range: 3–4 medications). All cases had IOP >22 mmHg despite using IOP lowering medications. Mean postoperative IOP decreased to 20.0 ± 6.4 mmHg (range: 15.0–35.0 mmHg) with a mean of 2.5 ± 1.1 (range: 0–4) medications. [Table 2] represents the IOP over the postoperative visits. The IOP, differed statistically significantly at different times when analyzed with ANOVA using Bonferroni adjustment. However, using Tukey's post-hoc test, a statistically significant difference was observed only for comparison between preoperative and postoperative IOPs at different times (P < 0.0001), and there was no statistically significant difference between IOP measurements comparing different postoperative visits.
Table 2: Intraocular pressure and number of medications preoperatively and postoperatively

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In life-table survival analysis and based on the predefined success criteria, qualified success was achieved in 69% of subjects at the end of 120 months of follow-up. The mean ± standard error of mean time to failure according to complete and qualified success criteria was 51.6 ± 6.8 months and 92.3 ± 9.4 months, respectively [Figure 1].
Figure 1: Survival curve of complete success following Ahmed glaucoma valve implantation in 28 eyes with refractory glaucoma (a) complete success, (b) qualified success

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On average, visual acuity decreased by one Snellen line at the last postoperative visit. Mean preoperative visual acuity was 0.62 ± 0.43 logarithm of the minimum angle of resolution units and statistically significantly decreased to 0.76 ± 0.49 at last follow-up visit (P = 0.007). The visual acuity remained unchanged in 12 (42.9%) eyes, improved in 6 (21.4%) eyes, and decreased in 10 (35.7%) eyes (P < 0.0001).

No major intraoperative complications were recorded. Postoperative complications occurred in 16 (57.1%) eyes [Table 3]. The most common complication was focal endothelial corneal decompensation due to tube-cornea touch in 3 (10.7%) eyes. This complication was managed with surgical tube revision. Two aphakic eyes had vitreous incarceration in the tube orifice and were managed with neodymium-doped/yttrium aluminum garnet vitreolysis. AGV tube was extruded in two cases, which were managed with scleral patch graft and conjunctival advancement.
Table 3: Postoperative surgical complications following Ahmed glaucoma valve implantation in 28 Iranian eyes with refractory glaucoma

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Qualified success was achieved in 77.8%, 69.2%, and 66.7% of phakic, pseudophakic and aphakic eyes, respectively (P = 0.871).

[Table 4] compares the results of the current study with the results of previously published articles.
Table 4: Summary of previous published study on surgical outcome of glaucoma drainage devices along with the result of current study

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   Discussion Top

In the current study, we retrospectively reviewed the results of AGV implantation in Iranian patients with refractory glaucoma. In this series of 28 patients with a median follow-up time of 40.5 months, 69% of eyes achieved qualified success. However, various complications were encountered in almost 57% of cases during follow-up.

Surgical success rates for glaucoma shunting procedures vary in published studies from 20%[32] to 98%.[20] However, because of differences in the study population, type of implants, and the duration of follow-up, the results are not directly comparable to our study. Hence, it is tenous at best to make a globally valid conclusion about the efficacy of the procedure for the refractory glaucoma cases. The majority of the current body of literature regarding the success of drainage devices is from the developed countries, whereas refractory glaucoma seems to be more prevalent and disabling in developing and undeveloped countries.[33] The current study focused on the long-term success of AGV shunting procedure in refractory glaucoma cases in Iran.

[Table 4] presents the outcomes of previous studies on tube shunt implantation including our study. The differences on types of races of the study population could explain the variations in success rate between studies. Interestingly, a large multicenter study by Gedde et al.[17] (tube vs. trabeculectomy study [TVT]) had compared outcomes of primary shunting procedure, using 350 mm [2] Baerveldt glaucoma implant in 107 eyes, and trabeculectomy with mitomycin C in 105 eyes. The cumulative probability of failure for tube shunt (vs. trabeculectomy) during 1st year, first 3 years, and first 5 years of follow-up was, 3.9% (vs. 13.5%), 15.1% (vs. 30.7%), and 29.8% (vs. 46.9%), respectively.[2],[34],[35] They [17] concluded that tube shunts had a higher success rate than trabeculectomy in their cohort of patients. The cumulative probability of failure in the current study at 1-year, 3-year, and 5-year follow-up was 14%, 31%, and 31%, respectively. These rates are higher than the TVT study.[17] Syed et al.[26] reported similar surgical outcomes for the Ahmed and Baerveldt implants, and we believed that the observed differences are because we included eyes with failed previous incisional surgeries in our study. Souza et al.[6] retrospectively evaluated 78 eyes with AGV implant and proposed that prior glaucoma surgery could increase the risk of failure of AGV implantation by more than three-fold.

In the current study, postoperative complications occurred in 57.1% of eyes. We implanted silicon type AGV (AGV FP7) in our patients that may be associated with a higher complication rate.[36] However, there was no major tube-related visual loss in our patients, and our complication rate is comparable to previous studies [Table 4].

Limitations of this study include the retrospective design and the small sample-size. Another drawback was our inclusion of only subjects with previously failed incisional surgeries and refractory glaucoma in the study. Additionally, the study population was heterogeneous in terms of the type of glaucoma and duration of follow-up. Farabi Eye Hospital is the largest Referral Eye Hospital in Iran, and many patients went for further management to the referring ophthalmologist after a few postoperative visits. Hence, we had a high rate of patient dropout. However, our study has the largest follow-up of AGV implantation in the region.

   Conclusions Top

We believed that AGV implantation could have an acceptable success rate in patients with refractory glaucoma and failed previous incisional glaucoma surgery in patients in the Middle East. However, to achieve adequate IOP control, topical anti-glaucoma medications should be continued postoperatively in most subjects. A further implication of the current study is the need for periodic, long-term follow-up for proper management of failures or complications. After the 1st postoperative month, we suggest follow-up visits every 3 months in the 1st year, then every 6 months over the next 4 years, and annually thereafter. However, this recommendation should be further validated and should be tailored according to clinical judgments on many factors including but not limited to the severity of glaucomatous damage, level of IOP, general health of patients, and life expectancy.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol 2006;90:262-7.  Back to cited text no. 1
Gedde SJ, Schiffman JC, Feuer WJ, Herndon LW, Brandt JD, Budenz DL, et al. Treatment outcomes in the Tube Versus Trabeculectomy (TVT) study after five years of follow-up. Am J Ophthalmol 2012;153:789-803.e2.  Back to cited text no. 2
Molteno AC, Bevin TH, Herbison P, Husni MA. Long-term results of primary trabeculectomies and Molteno implants for primary open-angle glaucoma. Arch Ophthalmol 2011;129:1444-50.  Back to cited text no. 3
Tran DH, Souza C, Ang MJ, Loman J, Law SK, Coleman AL, et al. Comparison of long-term surgical success of Ahmed valve implant versus trabeculectomy in open-angle glaucoma. Br J Ophthalmol 2009;93:1504-9.  Back to cited text no. 4
Coleman AL, Hill R, Wilson MR, Choplin N, Kotas-Neumann R, Tam M, et al. Initial clinical experience with the Ahmed glaucoma valve implant. Am J Ophthalmol 1995;120:23-31.  Back to cited text no. 5
Souza C, Tran DH, Loman J, Law SK, Coleman AL, Caprioli J. Long-term outcomes of Ahmed glaucoma valve implantation in refractory glaucomas. Am J Ophthalmol 2007;144:893-900.  Back to cited text no. 6
Kaya M, Ozbek Z, Yaman A, Durak I. Long-term success of Ahmed glaucoma valve in refractory glaucoma. Int J Ophthalmol 2012;5:108-12.  Back to cited text no. 7
Jacob J, Stalmans I, Zeyen T. Ahmed and Baerveldt glaucoma drainage implants: Long-term results and factors influencing outcome. Bull Soc Belge Ophtalmol 2009;313:19-29.  Back to cited text no. 8
Wishart PK, Choudhary A, Wong D. Ahmed glaucoma valves in refractory glaucoma: A 7-year audit. Br J Ophthalmol 2010;94:1174-9.  Back to cited text no. 9
Budenz DL, Gedde SJ, Brandt JD, Kira D, Feuer W, Larson E. Baerveldt glaucoma implant in the management of refractory childhood glaucomas. Ophthalmology 2004;111:2204-10.  Back to cited text no. 10
Ceballos EM, Parrish RK 2nd, Schiffman JC. Outcome of Baerveldt glaucoma drainage implants for the treatment of uveitic glaucoma. Ophthalmology 2002;109:2256-60.  Back to cited text no. 11
Coleman AL, Smyth RJ, Wilson MR, Tam M. Initial clinical experience with the Ahmed glaucoma valve implant in pediatric patients. Arch Ophthalmol 1997;115:186-91.  Back to cited text no. 12
Da Mata A, Burk SE, Netland PA, Baltatzis S, Christen W, Foster CS. Management of uveitic glaucoma with Ahmed glaucoma valve implantation. Ophthalmology 1999;106:2168-72.  Back to cited text no. 13
Das JC, Chaudhuri Z, Sharma P, Bhomaj S. The Ahmed glaucoma valve in refractory glaucoma: Experiences in Indian eyes. Eye (Lond) 2005;19:183-90.  Back to cited text no. 14
de Guzman MH, Valencia A, Farinelli AC. Pars plana insertion of glaucoma drainage devices for refractory glaucoma. Clin Experiment Ophthalmol 2006;34:102-7.  Back to cited text no. 15
Every SG, Molteno AC, Bevin TH, Herbison P. Long-term results of Molteno implant insertion in cases of neovascular glaucoma. Arch Ophthalmol 2006;124:355-60.  Back to cited text no. 16
Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC, et al. Postoperative complications in the Tube Versus Trabeculectomy (TVT) study during five years of follow-up. Am J Ophthalmol 2012;153:804-14.e1.  Back to cited text no. 17
Hodkin MJ, Goldblatt WS, Burgoyne CF, Ball SF, Insler MS. Early clinical experience with the Baerveldt implant in complicated glaucomas. Am J Ophthalmol 1995;120:32-40.  Back to cited text no. 18
Huang MC, Netland PA, Coleman AL, Siegner SW, Moster MR, Hill RA. Intermediate-term clinical experience with the Ahmed glaucoma valve implant. Am J Ophthalmol 1999;127:27-33.  Back to cited text no. 19
Ishida K, Netland PA. Ahmed glaucoma valve implantation in African American and white patients. Arch Ophthalmol 2006;124:800-6.  Back to cited text no. 20
Lai JS, Poon AS, Chua JK, Tham CC, Leung AT, Lam DS. Efficacy and safety of the Ahmed glaucoma valve implant in Chinese eyes with complicated glaucoma. Br J Ophthalmol 2000;84:718-21.  Back to cited text no. 21
Lima FE, Magacho L, Carvalho DM, Susanna R Jr, Avila MP. A prospective, comparative study between endoscopic cyclophotocoagulation and the Ahmed drainage implant in refractory glaucoma. J Glaucoma 2004;13:233-7.  Back to cited text no. 22
Malik R, Ellingham RB, Suleman H, Morgan WH. Refractory glaucoma – Tube or diode? Clin Experiment Ophthalmol 2006;34:771-7.  Back to cited text no. 23
Minckler DS, Heuer DK, Hasty B, Baerveldt G, Cutting RC, Barlow WE. Clinical experience with the single-plate Molteno implant in complicated glaucomas. Ophthalmology 1988;95:1181-8.  Back to cited text no. 24
Molteno AC, Sayawat N, Herbison P. Otago glaucoma surgery outcome study: Long-term results of uveitis with secondary glaucoma drained by Molteno implants. Ophthalmology 2001;108:605-13.  Back to cited text no. 25
Syed HM, Law SK, Nam SH, Li G, Caprioli J, Coleman A. Baerveldt-350 implant versus Ahmed valve for refractory glaucoma: A case-controlled comparison. J Glaucoma 2004;13:38-45.  Back to cited text no. 26
Topouzis F, Coleman AL, Choplin N, Bethlem MM, Hill R, Yu F, et al. Follow-up of the original cohort with the Ahmed glaucoma valve implant. Am J Ophthalmol 1999;128:198-204.  Back to cited text no. 27
Tsai JC, Johnson CC, Kammer JA, Dietrich MS. The Ahmed shunt versus the Baerveldt shunt for refractory glaucoma II: Longer-term outcomes from a single surgeon. Ophthalmology 2006;113:913-7.  Back to cited text no. 28
Wilson MR, Mendis U, Smith SD, Paliwal A. Ahmed glaucoma valve implant vs trabeculectomy in the surgical treatment of glaucoma: A randomized clinical trial. Am J Ophthalmol 2000;130:267-73.  Back to cited text no. 29
Wilson MR, Mendis U, Paliwal A, Haynatzka V. Long-term follow-up of primary glaucoma surgery with Ahmed glaucoma valve implant versus trabeculectomy. Am J Ophthalmol 2003;136:464-70.  Back to cited text no. 30
WuDunn D, Phan AD, Cantor LB, Lind JT, Cortes A, Wu B. Clinical experience with the Baerveldt 250-mm2 Glaucoma implant. Ophthalmology 2006;113:766-72.  Back to cited text no. 31
Yalvac IS, Eksioglu U, Satana B, Duman S. Long-term results of Ahmed glaucoma valve and Molteno implant in neovascular glaucoma. Eye (Lond) 2007;21:65-70.  Back to cited text no. 32
Thomas R. Glaucoma in developing countries. Indian J Ophthalmol 2012;60:446-50.  Back to cited text no. 33
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Gedde SJ, Schiffman JC, Feuer WJ, Herndon LW, Brandt JD, Budenz DL. Treatment outcomes in the tube versus trabeculectomy study after one year of follow-up. Am J Ophthalmol 2007;143:9-22.  Back to cited text no. 34
Gedde SJ, Schiffman JC, Feuer WJ, Herndon LW, Brandt JD, Budenz DL, et al. Three-year follow-up of the tube versus trabeculectomy study. Am J Ophthalmol 2009;148:670-84.  Back to cited text no. 35
Law SK, Nguyen A, Coleman AL, Caprioli J. Comparison of safety and efficacy between silicone and polypropylene Ahmed glaucoma valves in refractory glaucoma. Ophthalmology 2005;112:1514-20.  Back to cited text no. 36


  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4]

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