Sequential Glaucoma Implants in Refractory Glaucoma AASHISH ANAND, CELSO TELLO, PAUL A. SIDOTI, ROBERT RITCH, AND JEFFREY M. LIEBMANN ● PURPOSE: To evaluate the efficacy of a second glaucoma implant in eyes with prior glaucoma implant surgery and inadequate intraocular pressure (IOP) control. ● DESIGN: Retrospective observational cohort study. ● METHODS: Patients undergoing a second glaucoma implant surgery from 1996 to 2008 were included. Outcome measures included visual acuity, IOP, glaucoma medication use, and complications. Success was defined as IOP < 21 mm Hg (criterion 1) and IOP < 17 mm Hg (criterion 2), with at least 25% reduction in IOP and no prolonged hypotony. ● RESULTS: Forty-three eyes (43 patients) had a mean follow-up of 32.6 ⴞ 21.6 months. Life-table analysis demonstrated success rates of 93%, 89%, and 83% using criterion 1 and 83%, 75%, and 75% using criterion 2 at 1, 2, and 3 years, respectively. At last follow-up, mean IOP (13.6 ⴞ 4.6 vs 24.7 ⴞ 7.5 mm Hg; P < .001) and mean number of medications (1.4 ⴞ 1.2 vs 3.9 ⴞ 1.2; P < .001) were lower following the second implant. There was no difference in preoperative and most recent logarithm of the minimal angle of resolution (logMAR) visual acuities (0.86 ⴞ 0.13 vs 1.1 ⴞ 0.13; P ⴝ .07). The most frequently used second implants were similar in percentage IOP reduction (Baerveldt implant, 45 ⴞ 19%; Ahmed valve, 40 ⴞ 18%; P ⴝ .4). ● CONCLUSIONS: A second glaucoma implant may effectively lower IOP in eyes with refractory glaucoma. (Am J Ophthalmol 2010;149:95–101. © 2010 by Elsevier Inc. All rights reserved.)
T
HE MOST COMMON CURRENT INDICATION FOR GLAU-
coma drainage device (GDD) implantation is uncontrolled glaucoma with intraocular pressure (IOP) refractory to medical therapy, laser treatment, and filtering surgery.1 Successful outcome following GDD implantation has been reported in 50% to 90% of patients depending on the severity of glaucoma, length of followup, and definition of success.2–7 A glaucoma implant may fail to adequately control IOP for some patients. Failure to achieve the target IOP is most often attributable to excessive fibrosis around the reservoir.8 Shunt revision surgery has been attempted for these eyes with limited long-term success rates.9 However, in Accepted for publication Jul 16, 2009. From the New York Eye and Ear Infirmary (A.A., C.T., P.A.S., R.R., J.M.L.), New York, New York; the New York Medical College (C.T., P.A.S., R.R.), Valhalla, New York; and the New York University School of Medicine (J.M.L.), New York, New York. Inquiries to Jeffrey M. Liebmann, 310 East 14th Street, New York, New York 10003; e-mail:
[email protected] 0002-9394/10/$36.00 doi:10.1016/j.ajo.2009.07.019
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2010 BY
many cases with inadequate IOP control following primary GDD implantation, surgical options may be limited to cyclophotocoagulation or placement of a second aqueous shunt. Although there are several reports of a favorable outcome after cyclodestructive procedures in refractory glaucomas with good visual potential,10 –12 many surgeons are hesitant to destroy the ciliary body because of the risks of uveitis, vision loss, hypotony, and phthisis. Complication rates have been reported to be relatively lower with endocyclophotocoagulation (ECP) compared with transscleral cyclophotocogulation (TCP).11,13 However, large studies with long-term follow-up are lacking. Alternatively, implantation of a second GDD may be performed. Data regarding the efficacy and potential complications associated with the implantation of an additional GDD is limited to three small retrospective studies published between 2000 and 2002.9,14,15 The purpose of this report is to assess the effectiveness and complications of sequential GDD implantation in consecutive patients with refractory glaucoma undergoing this procedure.
METHODS WE REVIEWED THE SURGICAL RECORDS OF ALL PATIENTS
undergoing GDD implantation at the New York Eye and Ear Infirmary between January 1, 1996 and January 1, 2008 to identify patients with sequential tube implants. These patients had undergone a second tube implant for inadequate IOP control despite the use of maximal tolerated medical therapy. Inclusion criteria included both implant surgeries having been performed by a glaucoma specialist at the New York Eye and Ear Infirmary and at least 12 months of follow-up after the second surgery. One eye was randomly selected for patients with bilateral sequential tube implants. Demographic, clinical, and operative details were extracted from the medical record. Details of IOP control, glaucoma medications, surgical complications, and visual acuity (VA) were collected at baseline assessment, before the second implant, and at each postoperative visit. The interval from baseline assessment to the first aqueous shunt, the first to second aqueous shunt, and the second shunt to most recent follow-up were determined. The primary outcome measure was IOP control. Secondary outcome measures included number of glaucoma medications, VA, and surgical complications. Success was defined as IOP ⬍ 21 mm Hg with at least 25% reduction
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TABLE 1. Baseline Demographics and Clinical Characteristics of Patients with Sequential Glaucoma Implants in Refractory Glaucoma
TABLE 2. Characteristics of Initial and Sequential Glaucoma Implants in Refractory Glaucoma
Demographics
Mean age in years (range) Gender Males Females Race Caucasian Black Hispanic Asian Glaucoma diagnosis POAG Secondary OAG CACG NVG Uveitic glaucoma Congenital glaucoma Angle recession Mixed-mechanism glaucoma ICE syndrome Aniridia Lens status Phakic Pseudophakia Aphakia
Type of implants Ahmed Baerveldt Moltenoa Krupin Schocket Location of tube Anterior chamber Sulcus/vitreous cavity Location of plate Supero-temporal Supero-nasal Infero-temporal Infero-nasal
52.8 ⫾ 22.9 (5 to 87) 23 (53.5%) 20 (46.5%) 24 (55.8%) 11 (25.8%) 5 (11.6%) 3 (6.9%) 16 (37.2%) 6 (14.0%) 2 (4.7%) 2 (4.7%) 4 (9.3%) 4 (9.3%) 3 (7.0%) 4 (9.3%) 1 (2.6%) 1 (2.6%)
First Implant
Second Implant
14 (32.6%) 22 (51.2%) 5 (11.6%) 1 (2.3%) 1 (2.3%)
17 (39.5%) 24 (55.8%) 2 (4.7%) 0 0
32 (74.4%) 11 (25.6%)
22 (51.2%) 21 (48.8%)
37 (86.0%) 3 (7.0%) 2 (4.7%) 1 (2.3%)
2 (4.7%) 17 (39.5%) 8 (18.6%) 16 (37.2%)
a
Single-plate Molteno.
analysis was performed using Kaplan-Meier estimates. A P value of .05 or less was considered statistically significant. To compare groups based on implant types, our sample size of 43 eyes could detect an 8% difference in mean percentage IOP reduction and a 3.75 mm Hg difference in mean IOP with different implant types with a two-sided level of significance of .05 and a power of 0.80.
4 (9.3%) 35 (81.4%) 4 (9.3%)
CACG ⫽ chronic angle closure glaucoma; ICE ⫽ iridocorneal endothelial syndrome; NVG ⫽ neovascular glaucoma; OAG ⫽ open-angle glaucoma; POAG ⫽ primary open- angle glaucoma.
RESULTS FIFTY-FIVE EYES OF 52 PATIENTS UNDERWENT SEQUENTIAL
in IOP on equal or less number of antiglaucoma drops and no prolonged hypotony (IOP ⬍ 4 mm Hg persisting for more than 8 weeks and/or associated hypotony related complications). A second criterion for success was defined as IOP ⬍ 17 mm Hg with at least 25% reduction in IOP on equal or less number of antiglaucoma drops and no prolonged hypotony. Snellen VA was converted to logarithm of the minimal angle of resolution (logMAR) equivalent for purpose of analysis. IOPs were reported both as absolute values and as percentage reduction from baseline. The mean of the last three IOP measurements taken before GDD surgery was used to report preoperative IOP. The means of IOP measurements between 3 and 6 months postoperatively and between 6 and 12 months postoperatively were used to report IOP at 6 months and 12 months, respectively. IOPs for subsequent postoperative years were reported by averaging all IOP measurements during that year. Measurements in the first 3 postoperative months were not used to calculate mean IOP for any time point. Statistical analysis was performed using paired two-sided t test or analysis of variance for continuous variables and 2/Fisher exact test for categorical variables. Life-table 96
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tube implantation between January 1, 1996 and January 1, 2008. Of these, 43 eyes met the inclusion criteria and were selected for analysis. Five excluded eyes had less than 12 months follow-up and 4 excluded eyes had the initial glaucoma implant surgery performed elsewhere. Table 1 shows the demographic and clinical profiles of the study population. Mean number of incisional intraocular surgeries before any tube implants was 2.6 ⫾ 1.2. Previous surgeries included failed trabeculectomy in 41 (95.3%) eyes, cataract surgery in 39 (90.7%) eyes, penetrating keratoplasy (PK) in 4 (9.3%) eyes, pars plana vitrectomy in 7 (16.3%) eyes, and goniotomy in 2 (4.7%) eyes. Repeat trabeculectomy or trabeculectomy revision had been performed in 19 (44.2%) eyes. Cataract surgery had been performed by a phacoemulsification procedure through clear corneal incision in 33 (84.6%) eyes, an extracapsular cataract extraction in 3 (7.7%), eyes and a pars plana lensectomy in 3 (7.7%) eyes. Initial GDD implantation included Baerveldt implant (Advanced Medical Optics Inc, Santa Ana, California, USA) in 22 (51.2%) eyes, Ahmed valve (New World Medical Inc, Rancho Cucamonga, California, USA) in 14 (32.6%) eyes, Molteno implant (Molteno Ophthalmics Ltd, Dunedin, New ZeaOF
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TABLE 3. Mean Intraocular Pressure and Glaucoma Drops Following Sequential Glaucoma Implant in Refractory Glaucoma IOP (mm Hg)
Glaucoma Drops (n)
Duration
Mean
Range
P value
Mean
Range
P value
Preoperative 6m 12 m 24 m 36 m 48 m 60 m 72 m
24.7 ⫾ 7.5 15.1 ⫾ 4.4 13.7 ⫾ 5.0 13.2 ⫾ 4.3 12.2 ⫾ 4.5 13.2 ⫾ 5.2 13.4 ⫾ 2.8 11.7 ⫾ 4.0
11.0 to 50.0 5.3 to 24.3 5.0 to 23.0 5.0 to 20.0 5.2 to 18.0 8.7 to 17.5 8.7 to 17.5 7.0 to 15.8
⬍.001 ⬍.001 ⬍.001 ⬍.001 .001 .01 .03
3.9 ⫾ 1.2 1.4 ⫾ 1.1 1.5 ⫾ 1.1 1.8 ⫾ 1.2 1.4 ⫾ 1.1 1.5 ⫾ 1.2 1.5 ⫾ 1.1 1.8 ⫾ 1.0
0 to 6.0 0 to 4.0 0 to 4.0 0 to 4.0 0 to 4.0 0 to 4.0 0 to 3.0 1.0 to 3.0
⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.01 .07
IOP ⫽ intraocular pressure; m ⫽ months. P value was derived from paired t test comparison between preoperative mean IOP and postoperative mean IOP for that period; 2 eyes with persistent hypotony were excluded from analysis.
FIGURE 1. Survival curves for sequential glaucoma implant in refractory glaucoma. Outcome criterion for survival curve 1 was intraocular pressure (IOP) < 21 mm Hg, > 25% reduction in IOP with equal or less glaucoma drops, and no hypotony. Outcome criterion for survival curve 2 was IOP < 17 mm Hg, > 25% reduction in IOP with equal or less glaucoma drops, and no hypotony.
land) in 5 (11.6%) eyes, Krupin valve (Eagle Vision Inc, Memphis, Tennessee, USA) in one eye, and Schocket implant in one eye. The mean duration between the first and second GDD surgery was 47.9 ⫾ 27.7 months. Second implants included Baerveldt implant in 24 (55.8%) eyes, Ahmed valve in 17 (39.5%) eyes, and Molteno implant in 2 (4.7%) eyes. The sequential GDD implantation was a second glaucoma surgery in 2 (4.7%) eyes, third glaucoma surgery in 21(48.8%) eyes, fourth glaucoma surgery in 19 (44.2%) eyes, and fifth glaucoma surgery in 1 (2.3%) eye. The mean follow-up following second tube implants was 32.6 ⫾ 21.6 months (range, 12 to 76 months). The details of shunt types, plate location, and tube placement are given in Table 2. VOL. 149, NO. 1
Baseline IOP before any device implantation was 31.2 ⫾ 10.0 mm Hg (range, 16 to 54 mm Hg). Mean number of antiglaucoma drops being used were 3.6 ⫾ 1.4 (range, 0 to 6). Twenty (46.5%) patients were using systemic carbonic anhydrase inhibitors. Mean IOP before the second GDD implantation was 24.7 ⫾ 7.5 mm Hg (range, 11 to 50 mm Hg). Mean number of antiglaucoma drops being used before the second implant was 3.9 ⫾ 1.2 (range, 0 to 6). Twenty-five (58.1%) patients were using systemic carbonic anhydrase inhibitors. Mean IOP and mean number of antiglaucoma drops at last follow-up following second implant were 13.6 ⫾ 4.6 mm Hg (range, 6 to 25 mm Hg) and 1.4 ⫾ 1.2 (range, 0 to 4), respectively. The mean percent reduction in IOP following the second implant was 44.1 ⫾ 18.1% (range, 4.7% to 82.2%). Four (9.3%) patients were on systemic carbonic anhydrase inhibitors at the last follow-up. Mean IOPs and mean number of antiglaucoma medications were significantly less at all intervals following second GDD implantation (Table 3). Kaplan-Meier life-table survival analysis was used to calculate success probabilities (Figure 1). Using outcome criterion 1, the probability of successful outcome was 92.9%, (95% confidence interval [CI], 99.8% to 84.8%; n ⫽ 43), 88.8% (95% CI, 99.6% to 75.6%; n ⫽ 39), and 83.2% (95% CI, 99.1% to 64.4%; n ⫽ 23) at 1, 2, and 3 years, respectively, following the second GDD surgery. Using outcome criterion 2, the probability of successful outcome was 83.3% (95% CI, 95.7% to 71.0%; n ⫽ 43), 75.3% (95% CI, 94.8% to 59.4%; n ⫽ 35), and 75.3% (95% CI, 98.6% to 54.4%; n ⫽ 20) at the same intervals. The most common sequential implant combinations in our series were Baerveldt-Ahmed in 11 (25.6%) eyes, Baerveldt-Baerveldt in 11 (25.6%) eyes, and AhmedBaerveldt in 11 (25.6%) eyes. Other implants combinations were Ahmed-Ahmed in 2 eyes, Ahmed-Molteno in 1 eye, Molteno-Baerveldt in 2 eyes, Molteno-Ahmed in 3 eyes, Krupin-Ahmed in 1 eye, and Schocket-Molteno in 1
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late endophthalmitis or tube exposure developed over a mean 33 months of follow-up. Persistent hypotony was seen in 2 (4.7%) cases. A 350 mm2 Baerveldt glaucoma implant was used both as initial and sequential implant in these eyes. Hypotony developed in the early postoperative period in one eye. This eye later developed rhegmatogenous retinal detachment requiring use of silicone oil. The second eye developed hypotony following a PK and tube repositioning in the vitreous cavity at the third postoperative year. Both eyes had undergone more than 5 incisional intraocular surgeries, including two trabeculectomies and a trabeculectomy revision, before the second tube placement. Progressive corneal decompensation occured in 7 (16.3%) eyes following second tube implants. Four of these 7 eyes had worsening of pre-existing pseudophakic bullous keratopathy and 2 eyes had preexisting failing corneal transplants. One patient experienced new onset corneal decompensation. Four of these eyes subsequently underwent PK.
FIGURE 2. IOP reduction with most common glaucoma implant combinations and second glaucoma implants in refractory glaucoma. Percentage IOP reduction was calculated from IOP before any implant surgery while comparing implant combinations and from immediate preoperative IOP before second surgery while comparing second implants.
DISCUSSION MANAGEMENT OF INADEQUATE IOP CONTROL FOLLOWING
aqueous shunt implantation in refractory glaucomas is challenging. There is very limited data on the clinical results with sequential GDDs, and most surgeons rely on their personal or anecdotal experiences and results from initial shunt surgeries when performing additional tube surgeries. The intraoperative and postoperative course of an additional implant, however, can be more unpredictable because of the presence of the first implant, extensive conjunctival scarring, and additional trauma to corneal endothelium. Therefore, outcome results of initial implant studies may not be accurately extrapolated to additional shunts. Table 4 summarizes clinical results of all studies on sequential tube shunts. In the first published series on additional tubes, Burgoyne and associates14 reported an average percentage IOP reduction of 42% from baseline following second tube in 22 eyes at a mean follow-up of 35 months. Fifty percent of their study population was primary open-angle glaucoma compared with 37% in our series. Shah and associates9 compared shunt revision in 12 eyes with second shunt placement in 21 eyes with a mean follow-up of 35 months in the additional tube subgroup. The mean preoperative IOP of 29.8 mm Hg dropped to a mean IOP of 17.7 mm Hg in the second tube group at the last follow-up. Godfrey and associates15 followed 18 patients for a mean of 21 months and found that a mean preoperative IOP of 29.5 mm Hg dropped to a mean IOP of 19.6 mm Hg at last follow-up following second aqueous shunt. In our series comprising 43 eyes with a mean follow-up of 33 months, mean preoperative IOP of 24.7 mm Hg before second shunt dropped to 13.6 mm Hg at
FIGURE 3. Correlation of total surface area of glaucoma implant combinations with percentage IOP reduction in refractory glaucoma.
eye. The most frequently used GDD combinations were similar in percentage IOP reduction from IOP before any device implantation (Baerveldt-Ahmed, 55%⫾14%; AhmedBaerveldt, 55%⫾18%; Baerveldt-Baerveldt, 53%⫾19%; P ⫽ .9) (Figure 2). The most frequently used second implants were similar in percentage IOP reduction from preoperative IOP before second implant surgery (Baerveldt, 45%⫾19%; Ahmed, 40%⫾18%; P ⫽ .4) (Figure 2). The combined plate surface area of both implants ranged from 325 mm2 to 700 mm2. No correlation was seen between the total combined implant surface area and percentage reduction in IOP (Figure 3). There was no difference in preoperative and most recent logMAR VAs (0.86⫾0.13 vs 1.1⫾0.13; P ⫽ .07). No major intraoperative complications were seen. No cases of 98
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TABLE 4. Clinical Results of Studies on Sequential Glaucoma Implants in Refractory Glaucoma
Author (year)
N
Study Design
Follow-up (months)
Burgoyne14 (2000)
22
RNCCS
35 (2 to 89)
Shah9 (2000)
21
RCCS
35 (6 to 84)
Godfrey15 (2002)
18
RNCCS
20 (6 to 47)
Anand
43
RNCCS
33 (12 to 76)
Definition of Success
Success Rate (3 years)
IOP ⬍21 mm Hg; 20% reduction in IOP 25% reduction in IOP
80%
IOP ⬍21 mm Hg; 20% reduction in IOP IOP ⬍21 mm Hg; 25% reduction in IOP
70%
37%a 83%
Complications
45% worsenedb or new PBK, 1 eye choroidal effusionc 43% new or worsening corneal edema, 19% had PKP, 2 eyes phthisis 28% PBK or graft failure 16.3% worsened or new PBK or graft failure, 2 eyes with persistent late hypotony
PBK ⫽ pseudophakic bullous keratopathy; PKP ⫽ penetrating keratoplasty; RCCS ⫽ retrospective comparative case series; RNCCS ⫽ retrospective noncomparative case series. a Mean follow-up of 19.6 months. b Drop in 2 or more lines on Snellen chart postoperatively. c Large choroidal effusion requiring drainage.
most recent follow-up following the second tube. Second GDDs resulted in a 44% reduction in IOP from the preoperative IOP. Two of the previous studies9,14 reported significant reductions in concomitant medical therapy at the last follow-up, while no statistical difference was found in one study15 at the last follow-up. In our study, the mean number of glaucoma medications dropped significantly following the second tube implantation. Our 3-year success rates of 83% for the second tube are similar to an 80% success rate reported by Burgoyne and associates14 and a 70% success rate reported by Shah and associates.9 All three studies had a similar mean follow-up of 33 to 35 months and used comparable outcome criteria. Godfrey and associates15 report a 37% success rate at 3 years with a mean follow-up of 20 months. The Tube Versus Trabeculectomy Study group reported a drop in mean baseline IOP of 25.1 mm Hg to a mean IOP of 12.4 mm Hg at 12 months postoperatively following placement of a primary 350 mm2 Baerveldt glaucoma implant.16 There was a significant reduction in number of glaucoma medications from 3.2 at baseline to 1.3 at 12 months. In a randomized controlled trial comparing Ahmed valve implant with trabeculectomy, mean baseline IOP of 25.9 mm Hg dropped to mean IOP of 12.5 mm Hg at 36 months postoperatively following placement of a primary Ahmed implant.17 The IOP reduction achieved by these implants appears similar when used in initial or sequential glaucoma surgery. In primary implant studies, two-plate Molteno implants provided better IOP control than single-plate implants.18 However, a randomized controlled trial comparing 350 mm2 and 500 mm2 Baerveldt implants as primary shunts found superior IOP control with the 350 mm2 implant.19 Despite general consensus that large-surface area implants VOL. 149, NO. 1
may provide better IOP control, superiority of any implant type could not be proven in a meta-analysis.7 Godfrey and associates15 did not find any significant difference in mean survival time of large (⬎ 250 mm2) and small (⬍ 250 mm2) GDDs when used as a second implant. Shah and associates9 observed that single-plate Molteno implant as additional GDD had a lower success rate compared with double-plate Molteno, Ahmed, and Baerveldt implants. However, their numbers in each subgroup were too small for statistical comparison. We attempted to identify any implant types and/or implant combinations with better outcome than others when used in sequential tube surgeries. Our three most commonly used implant combinations, Baerveldt-Ahmed, Ahmed-Baerveldt, and Baerveldt-Baerveldt, were statistically similar in percentage IOP reduction from baseline IOP before any implant surgery. We did not find any correlation between total surface area of both implants with percent IOP reduction. Our two most commonly used implants (Baerveldt implant and Ahmed valve) were similar in percent IOP reduction until the last follow-up. Previous studies have described corneal decompensation as the most significant complication following sequential tubes. Earlier series report a 25% to 45% incidence of corneal decompensation following second aqueous shunts.9,14,15 The mean number of intraocular surgeries before second tubes were reported in the range of 3 to 3.5. Considering the number of previous surgical procedures, laser procedures, and poor IOP control, it is not surprising that a substantial number of corneas decompensated. Our corneal decompensation/graft failure rates of 16.3% were lower than previous reports. However, nearly 50% of our second tubes were implanted in the sulcus or vitreous cavity. Godfrey and associates15 had a similar prevalence of pseudophakia/aphakia in their series. All tubes in their
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study were placed in the anterior chamber through a scleral tunnel. The other two reports on sequential implants have not described the location of their tubes. There is evidence from studies on initial implants that sulcus or pars plana placement of tubes may lower the risk of corneal decompensation.20 –22 It is difficult to say if our lower rates are related to different patient profile or to preferential placement of second tubes in the posterior segment. A potential complication of sequential tubes is overfiltration resulting in hypotony and related complications. Burgoyne and associates14 report one case of appositional choroidal effusions requiring drainage in their series. Shah and associates9 described phthisis in 2 eyes and choroidal effusion requiring drainage in 1 eye in their additional tube subgroup. Two eyes in our series had persistent hypotony. There were no identifiable risk factors for developing hypotony following sequential GDD placement. However, both eyes with hypotony in our series had undergone more than 5 intraocular surgeries before the second tube placement. Within the constraints of a retrospective design, we cannot determine with certainty (slit-lamp confirmation or ultrasound imaging) between partially functional (ie, any flow through the tube/valve into the fibrous capsule surrounding the drainage plate) or completely failed implants.
Our data suggests presence of partial function for most of the initial implants in our series. In such cases, the postoperative IOP likely represents an additive effect of both implants. The possibility of any bias introduced by the unequal distribution in different implant combination subgroups should be kept in mind while interpreting outcomes of different implant combinations in our series. The most common second implants, Baerveldt and Ahmed, had similar outcomes in our study. Again, these results may only hold true for our most common implant combinations. Our data does not support similar outcome of Baerveldt and Ahmed implants in any other implant combination. The outcome of different implants seen in the study could be biased because of unequal and unmatched groups. The possibility of any bias introduced by heterogeneity of our study population with respect to initial diagnosis, type of first implant, and lens status cannot be ruled out. In summary, sequential glaucoma implants have a good mid-term outcome and provide an effective and relatively safe means of treating inadequately controlled IOP following primary aqueous shunt. No particular implant type appears superior for this purpose.
THIS STUDY WAS SUPPORTED IN PART BY THE CORINNE S. GRABER RESEARCH FUND OF THE NEW YORK GLAUCOMA Research Institute, New York, New York. The authors indicate no financial conflict of interest. Involved in design of study (A.A., J.M.L.); conduct of study (A.A., C.T., P.A.S., R.R., J.M.L.); data collection (A.A.); management (A.A., J.M.L.), analysis (A.A.), and interpretation of data (A.A., C.S., P.A.S., R.R., J.M.L.); and preparation (A.A., J.M.L.), review (A.A., C.T., P.A.S., R.R., J.M.L.), and approval of manuscript (A.A., C.T., P.A.S., R.R., J.M.L.). The study was approved by the New York Eye and Ear Infirmary Institutional Review Board and followed the tenets of the Declaration of Helsinki.
8. Lavin MJ, Franks WA, Wormald RP, Hitchings RA. Clinical risk factors for failure in glaucoma tube surgery. A comparison of three tube designs. Arch Ophthalmol 1992;110:480 – 485. 9. Shah AA, WuDunn D, Cantor LB. Shunt revision versus additional tube shunt implantation after failed tube shunt surgery in refractory glaucoma. Am J Ophthalmol 2000;129: 455– 460. 10. Ansari E, Gandhewar J. Long-term efficacy and visual acuity following transscleral diode laser photocoagulation in cases of refractory and non-refractory glaucoma. Eye 2007;21:936 – 940. 11. Gayton JL, van De Karr M, Sanders V. Combined cataract and glaucoma surgery: trabeculectomy versus endoscopic laser cycloablation. J Cataract Refract Surg 1999;25:1214 – 1219. 12. Chen J, Cohn RA, Lin SC, et al. Endoscopic photocoagulation of the ciliary body for treatment of refractory glaucomas. Am J Ophthalmol 1997;124:787–796. 13. Lin SC. Endoscopic and transscleral cyclophotocoagulation for the treatment of refractory glaucoma. J Glaucoma 2008; 17:238 –247. 14. Burgoyne JK, WuDunn D, Lakhani V, Cantor LB. Outcomes of sequential tube shunts in complicated glaucoma. Ophthalmology 2000;107:309 –314. 15. Godfrey DG, Krishna R, Greenfield DS, Budenz DL, Gedde SJ, Scott IU. Implantation of second glaucoma drainage
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19. Britt MT, LaBree LD, Lloyd MA, et al. Randomized clinical trial of the 350-mm2 versus the 500-mm2 Baerveldt implant: longer term results: is bigger better? Ophthalmology 1999; 106:2312–2318. 20. Tello C, Espana EM, Mora R, Dorairaj S, Liebmann JM, Ritch R. Baerveldt glaucoma implant insertion in the posterior chamber sulcus. Br J Ophthalmol 2007;91:739 –742. 21. Varma R, Heuer DK, Lundy DC, Baerveldt G, Lee PP, Minckler DS. Pars plana Baerveldt tube insertion with vitrectomy in glaucomas associated with pseudophakia and aphakia. Am J Ophthalmol 1995;119:401– 407. 22. de Guzman MH, Valencia A, Farinelli AC. Pars plana insertion of glaucoma drainage devices for refractory glaucoma. Clin Experiment Ophthalmol 2006;34:102–107.
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