Practice patterns in glaucoma have shifted significantly among glaucoma providers in recent decades, with a substantial decrease in the use of trabeculectomy and a corresponding increase in the use of glaucoma drainage devices (GDDs).1–4 Part of the impetus for the shift has been attributed to findings from the Tube Versus Trabeculectomy (TVT) Study, which reported a higher incidence of early postoperative complications5 and a higher failure rate for the trabeculectomy group at 5 years.6
With the increased utilization of GDDs, there have been numerous studies comparing GDD types. Among them, the Ahmed Baerveldt Comparison (ABC) and the Ahmed Versus Baerveldt (AVB) Studies have been the largest multicenter randomized clinical trials, comparing patients with Baerveldt 350 (B350, Advanced Medical Optics) and those with Ahmed FP7 (FP7, New World Medical Inc.).7–9 Several retrospective studies have compared the various Baerveldt plate sizes (200, 250, 350, and 500 mm2),10 Ahmed S2 with Baerveldt 250 (B250) GDDs,11 B250 with B350 GDDs,12 and Molteno 230/245 with B250 and B350 GDDs.13 With the finding that bigger is not necessarily better in terms of clinical outcomes, many surgeons now favor the smaller Baerveldt GDDs for greater ease of placement and potentially lower incidence of postoperative diplopia.10,12–15 The purpose of the current study is to compare the surgical and clinical success rates in patients with GDDs that are now three of the most commonly used GDDs, the FP7, the B250, and the B350.
METHODS
This study was prospectively approved by the Institutional Review Board of the Mayo Clinic and the Olmsted Medical Center, Minnesota, and it conforms to the requirements of the United States Health Insurance Portability and Privacy Act. Informed consent was obtained from all patients in the study, and the study adhered to the tenets of the Declaration of Helsinki.
Patients and Controls
From August 2017 through July 2019, adult surgical glaucoma patients at a single institution tertiary referral glaucoma practice who had received FP7, B250, or B350GDDs, and medically controlled glaucoma patients, were consecutively enrolled at their regular glaucoma visits. Patients with multiple GDD in the same eye or GDD in quadrants other than superotemporal location were excluded. Medically controlled patients included those who received neither a GDD nor trabeculectomy, but may have undergone selective laser trabeculoplasty, trabectome, iStent (Glaukos), or cataract surgery. Control patients (115/190 eyes) who underwent ocular surgery after enrollment were included. Those enrolled also included those who had received GDDs at outside institutions.
Primary and Secondary Outcome Measures
The primary outcome measure was surgical failure, defined as intraocular pressure (IOP) >21 mm Hg, ≤5 mm Hg, or <20% reduction below baseline on 2 consecutive visits >3 months after GDD surgery, additional glaucoma surgery (GDD, tube revision, trabeculectomy, cyclodestruction, or trabeculotomy), GDD removal, or loss of light perception. Eyes that did not meet the above failure definitions and were not on any IOP-lowering medications were considered complete successes, while those requiring medical therapy were defined as qualified successes. Interventions such as bleb needling or laser suture lysis were not considered additional glaucoma surgery.
Clinical success, IOP, use of glaucoma medications, visual acuity (VA), and surgical complications and interventions were secondary outcome measures. Eyes that met their target IOP ranges and did not require additional glaucoma surgery were deemed to have attained clinical success. Eyes that did not meet either criterion were considered clinical failures. Baseline data were collected at the preoperative visit closest in time to the GDD surgery in the GDD groups, and upon enrollment for the medically treated control group.
Data Analysis
Patient demographics and clinical data were compared among the study groups using the Kruskal-Wallis test for continuous data and the χ2 test for categorical variables. Fishers exact test was used when the number of events was small in some of the groups. Overall surgical failure was estimated using the Kaplan-Meier approach. A comparison of those failure curves were completed with log-rank tests. All multiple pair-wise comparisons underwent Bonferroni corrections. SAS 9.04.01 (SAS Institute Inc.) was used to conduct the analyses.
RESULTS
Baseline Characteristics
A total of 347 eyes were enrolled in the 2-year study period (Table 1), with 43 (12.4%) FP7, 36 (10.4%) B250, 78 (22.5%) B350, and 190 (54.8%) medically treated control eyes. The FP7 group had a lower mean age (58.3 y, range 18–83) than the B250 (71.3 y, range 40–94, P=0.002) and the control (67.3 y, range 37–93), P=0.010) groups. About half of each of the groups were female (P=0.425), 83.3%–97.4% were Caucasian (P=0.004), and 41.7%–58.1% were right eyes (P=0.530). While most of the eyes in the B250, B350, and control groups had primary open angle glaucoma (51.3%–76.3%), the 3 main glaucoma types in the FP7 group were uveitic glaucoma and steroid response (32.6%), uveitic glaucoma alone (14.0%), neovascular glaucoma (14.0%).
TABLE 1 -
Baseline Demographics and Characteristics
|
FP7 (N=43) |
B250 (N=36) |
B350 (N=78) |
Ctrl (N=190) |
Total (N=347) |
P
|
| Age (y) |
|
|
|
|
|
0.001
*
|
| n |
41 |
36 |
76 |
190 |
343 |
|
| Mean (SD) |
58.3 (16.3) |
71.3 (12.0) |
65.3 (12.3) |
67.3 (11.2) |
66.2 (12.6) |
|
| Range |
(18–83) |
(40–94) |
(40–88) |
(37–93) |
(18–94) |
|
| Pairwise P
|
| FP7 |
— |
0.002
|
0.198 |
0.010
|
|
|
| B250 |
— |
— |
0.066 |
0.188 |
|
|
| B350 |
— |
— |
— |
1.00 |
|
|
| Sex, n (%) |
|
|
|
|
|
0.425†
|
| Female |
23 (53.5) |
23 (63.9) |
37 (47.4) |
97 (51.1) |
180 (51.9) |
|
| Race, n (%) |
|
|
|
|
|
0.004
†
|
| Missing |
3 |
0 |
1 |
0 |
4 |
|
| African American |
0 |
2 (5.6) |
0 (0.0) |
2 (1.1) |
4 (1.2) |
|
| Asian |
3 (7.5) |
2 (5.6) |
1 (1.3) |
4 (2.1) |
10 (2.9) |
|
| White |
37 (92.5) |
30 (83.3) |
75 (97.4) |
184 (96.8) |
326 (95.0) |
|
| Other |
0 |
2 (5.6) |
1 (1.3) |
0 (0.0) |
3 (0.9) |
|
| Pairwise P
|
| FP7 |
— |
1.00 |
0.376 |
1.00 |
|
|
| B250 |
— |
— |
1.00 |
1.00 |
|
|
| B350 |
— |
— |
— |
1.00 |
|
|
| Laterality, n (%) |
|
|
|
|
|
0.530†
|
| OD (right eye) |
25 (58.1) |
15 (41.7) |
40 (51.3) |
94 (49.5) |
174 (50.1) |
|
| Glaucoma type, n (%) |
|
|
|
|
|
<0.001
†
|
| Primary open angle |
4 (9.3) |
20 (55.6) |
40 (51.3) |
145 (76.3) |
209 (60.2) |
|
| Primary angle closure |
2 (4.7) |
3 (8.3) |
1 (1.3) |
4 (2.1) |
10 (2.9) |
|
| Juvenile open angle |
0 |
0 |
1 (1.3) |
0 |
1 (0.3) |
|
| Neovascular |
6 (14.0) |
0 |
1 (1.3) |
0 |
7 (2.0) |
|
| Glaucoma suspect |
0 |
0 |
0 |
2 (1.1) |
2 (0.6) |
|
| Secondary open angle |
5 (11.6) |
8 (22.2) |
19 (24.4) |
25 (13.2) |
57 (16.4) |
|
| Steroid-response |
3 (7.0) |
0 |
1 (1.3) |
0 |
4 (1.2) |
|
| Uveitic/steroid response |
14 (32.6) |
0 |
6 (7.7) |
0 |
20 (5.8) |
|
| Uveitic |
6 (14.0) |
1 (2.8) |
0 |
6 (3.2) |
13 (3.7) |
|
| Mixed mechanism |
2 (4.7) |
3 (8.3) |
4 (5.1) |
6 (3.2) |
15 (4.3) |
|
| Other |
1 (2.3) |
1 (2.8) |
5 (6.4) |
2 (1.1) |
9 (2.6) |
|
| Pairwise P
|
| FP7 |
— |
<0.001
|
<0.001
|
<0.001
|
|
|
| B250 |
— |
— |
1.00 |
0.074 |
|
|
| B350 |
— |
— |
— |
<0.001
|
|
|
| Baseline visual acuity |
|
|
|
|
|
<0.001
*
|
| N |
43 |
36 |
78 |
190 |
347 |
|
| Mean (SD), logMar |
0.8 (0.8) |
0.4 (0.5) |
0.5 (0.6) |
0.2 (0.4) |
0.4 (0.5) |
|
| Range |
(0.0–2.7) |
(0.0–2.0) |
(0.0–2.7) |
(−0.1, 2.6) |
(−0.1, 2.7) |
|
| Pairwise P
|
| FP7 |
— |
0.341 |
0.053 |
<0.001
|
|
|
| B250 |
— |
— |
1.00 |
0.018
|
|
|
| B350 |
— |
— |
— |
0.002
|
|
|
| Baseline IOP |
|
|
|
|
|
<0.001
*
|
| N |
41 |
35 |
76 |
190 |
342 |
|
| Mean (SD), mm Hg |
29.9 (11.2) |
17.3 (6.1) |
23.7 (9.6) |
17.8 (5.6) |
20.5 (8.6) |
|
| Range |
(9–55) |
(5–33) |
(10–56) |
(6–44) |
(5–56) |
|
| Pairwise P
|
| FP7 |
— |
<0.001
|
0.010
|
<0.001
|
|
|
| B250 |
— |
— |
0.004
|
1.00 |
|
|
| B350 |
— |
— |
— |
<0.001
|
|
|
| Baseline C:D ratio |
|
|
|
|
|
<0.001
*
|
| N |
40 |
36 |
75 |
185 |
336 |
|
| Mean (SD) |
0.6 (0.3) |
0.8 (0.2) |
0.8 (0.2) |
0.6 (0.2) |
0.7 (0.2) |
|
| Range |
(0.0–1.0) |
(0.3–1.0) |
(0.1–1.0) |
(0.1–1.0) |
(0.0–1.0) |
|
| Pairwise P
|
| FP7 |
— |
0.001
|
0.001
|
1.00 |
|
|
| B250 |
— |
— |
1.00 |
<0.001
|
|
|
| B350 |
— |
— |
— |
<0.001
|
|
|
| Baseline number of classes of glaucoma medication |
|
|
|
|
|
<0.001
*
|
| N |
43 |
36 |
77 |
190 |
346 |
|
| Mean (SD) |
3.4 (1.5) |
2.9 (1.6) |
3.3 (1.3) |
1.6 (1.2) |
2.3 (1.5) |
|
| Range |
(0–6) |
(0–6) |
(0–6) |
(0–5) |
(0–6) |
|
| Pairwise P
|
| FP7 |
— |
0.964 |
1.00 |
<0.001
|
|
|
| B250 |
— |
— |
1.00 |
<0.001
|
|
|
| B350 |
— |
— |
— |
<0.001
|
|
|
| No. previous surgeries |
|
|
|
|
|
<0.001
*
|
| N |
43 |
36 |
78 |
190 |
347 |
|
| Mean (SD) |
1.0 (1.3) |
1.9 (1.6) |
1.6 (1.5) |
0.2 (0.5) |
0.8 (1.2) |
|
| Range |
(0–6) |
(0–6) |
(0–5) |
(0–3) |
(0–6) |
|
| Pairwise P
|
| FP7 |
— |
0.046
|
0.298 |
<0.001
|
|
|
| B250 |
— |
— |
1.00 |
<0.001
|
|
|
| B350 |
— |
— |
— |
<0.001
|
|
|
| Prior cataract surgery, n (%) |
13 (30.2) |
11 (30.6) |
22 (28.2) |
29 (15.3) |
75 (21.6) |
0.018
†
|
| Pairwise P
|
| FP7 |
— |
1.00 |
1.00 |
0.129 |
|
|
| B250 |
— |
— |
1.00 |
0.168 |
|
|
| B350 |
— |
— |
— |
0.086 |
|
|
| Prior trabeculectomy, n (%) |
6 (14.0) |
12 (33.3) |
30 (38.5) |
0 (0.0) |
48 (13.8) |
<0.001
†
|
| Pairwise P
|
| FP7 |
— |
0.257 |
0.030
|
<0.001
|
|
|
| B250 |
— |
— |
1.00 |
<0.001
|
|
|
| B350 |
— |
— |
— |
<0.001
|
|
|
| Prior cataract surgery and MIGS, n (%) |
1 (2.3) |
2 (5.6) |
4 (5.1) |
0 |
7 (2.0) |
0.018
†
|
| Pairwise P
|
| FP7 |
— |
1.00 |
1.00 |
0.219 |
|
|
| B250 |
— |
— |
1.00 |
0.007
|
|
|
| B350 |
— |
— |
— |
0.010
|
|
|
| Prior trabeculoplasty, n (%) |
12 (27.9) |
20 (55.6) |
39 (50.0) |
9 (4.7) |
80 (23.1) |
<0.001
†
|
| Pairwise P
|
| FP7 |
— |
0.081 |
0.115 |
<0.001
|
|
|
| B250 |
— |
— |
1.00 |
<0.001
|
|
|
| B350 |
— |
— |
— |
<0.001
|
|
|
| Previous iridotomy, n (%) |
2 (4.7) |
5 (13.9) |
2 (2.6) |
1 (0.5) |
10 (2.9) |
<0.001
†
|
| Pairwise P
|
| FP7 |
— |
0.934 |
1.00 |
0.187 |
|
|
| B250 |
— |
— |
0.121 |
<0.001
|
|
|
| B350 |
— |
— |
— |
0.911 |
|
|
*Kruskal Wallis.
†Chi-Square.
Bold values indicates statistically significative (P<0.05)
Pairwise P values reflect the Bonferroni correction for multiple comparisons.
B250 indicates Baerveldt 250; B350, Baerveldt 350; IOP, intraocular pressure; MIGS, minimally invasive glaucoma surgeries.
At baseline, the GDD groups had worse mean VA than the control group (P<0.001) (Table 1). The FP7 group had the highest baseline mean IOPs (29.9 mm Hg, range 9–55) and the B350 group, the second highest (23.7 mm Hg, range 10–56). There was no significant difference between the mean baseline IOPs in the B250 (17.3 mm Hg, range 5–33) and the control (17.8 mm Hg, 6–44) groups (P=1.00). Baseline mean cup-to-disc ratios were similar between the B250 (0.8, range 0.3–1.0) and the B350 (0.8, range 0.1–1.0, P=1.00) groups, and the FP7 (0.6, range 0.0–1.0) and the control (0.6, range 0.1–1.0, P=1.00) groups. All the GDD groups had a higher baseline mean number of classes of glaucoma medications than the control group (P<0.001), but no significant differences between the 3 groups. All the GDD groups had higher baseline mean number of surgeries than the control group (P<0.001), and the B250 group had significantly higher mean number of surgeries than the FP7 group (P=0.046). There were significant differences among the 4 groups in rates of prior cataract surgeries with (P=0.018) or without minimally invasive glaucoma surgeries (P=0.018), trabeculectomy (P<0.001), trabeculoplasty (P<0.001), and iridotomy (P<0.001). The B350 group had a higher rate of prior trabeculectomy than the FP7 group, but not significantly different from the rate in the B250 group.
Clinical Outcomes
Postoperatively, there were no significant differences in VA, IOP, or number of classes of glaucoma medications between the GDD groups at postoperative month 6 (POM6), POM12, POY2, POY3, or the last visits, which were a mean of 2.5–3.5 years from the GDD surgery (Table 2, Figs. 1–3). Compared with the control group, all the GDD groups had worse mean VA (P<0.001) and mean deviation (P<0.001) at the last visits, but no significant difference in the mean number of glaucoma medications (P=0.223). Overall, there was a significant difference in mean IOP among the 4 groups (P=0.024), but not on pairwise comparisons.
TABLE 2 -
Postoperative Mean Visual Acuity, Intraocular Pressure, and Glaucoma Medication Use
|
FP7 (N=43) |
B250 (N=36) |
B350 (N=78) |
P
*
|
| Postoperative month 6 (POM6) time from GDD surgery, d |
|
|
|
0.638 |
| N |
36 |
25 |
62 |
|
| Mean (SD) |
178.5 (24.5) |
179.8 (25.1) |
176.5 (21.2) |
|
| Range |
(113.0–219.0) |
(114.0–224.0) |
(128.0–220.0) |
|
| POM6 visual acuity, logMar |
|
|
|
0.120 |
| N |
36 |
25 |
62 |
|
| Mean (SD) |
0.4 (0.6) |
0.6 (0.7) |
0.3 (0.4) |
|
| Range |
(0.0–2.4) |
(0.0–2.4) |
(0.0–2.0) |
|
| POM6 intraocular pressure, mm Hg |
|
|
|
0.422 |
| N |
35 |
25 |
62 |
|
| Mean (SD) |
13.8 (4.8) |
12.6 (5.8) |
14.8 (8.9) |
|
| Range |
(5.0–24.0) |
(4.0–27.0) |
(4.0–70.0) |
|
| POM6 number of classes of glaucoma meds |
|
|
|
0.992 |
| N |
36 |
24 |
62 |
|
| Mean (SD) |
1.9 (1.1) |
1.8 (1.2) |
1.9 (1.3) |
|
| Range |
(0.0–4.0) |
(0.0–4.0) |
(0.0–5.0) |
|
| Postoperative month 12 (POM12) |
| Time from GDD surgery, mo |
|
|
|
0.241 |
| N |
32 |
27 |
62 |
|
| Mean (SD) |
12.3 (1.2) |
12.4 (1.5) |
12.0 (1.1) |
|
| Range |
(9.6–14.5) |
(9.7–15.0) |
(9.6–14.8) |
|
| POM12 visual acuity, logMar |
|
|
|
0.755 |
| N |
33 |
27 |
62 |
|
| Mean (SD) |
0.4 (0.7) |
0.4 (0.6) |
0.4 (0.6) |
|
| Range |
(−0.1, 3.3) |
(0.0–2.5) |
(−0.1, 2.6) |
|
| POM12 intraocular pressure, mm Hg |
|
|
|
0.327 |
| N |
33 |
27 |
62 |
|
| Mean (SD) |
12.6 (4.6) |
11.6 (4.5) |
13.3 (6.0) |
|
| Range |
(3.0–23.0) |
(3.0–23.0) |
(2.0–31.0) |
|
| POM12 number of classes of glaucoma meds |
|
|
|
0.594 |
| N |
33 |
27 |
62 |
|
| Mean (SD) |
2.1 (1.0) |
1.8 (1.2) |
1.9 (1.3) |
|
| Range |
(0.0–4.0) |
(0.0–4.0) |
(0.0–4.0) |
|
| Postoperative year 2 (POY2) time from GDD surgery, mo |
|
|
|
0.956 |
| N |
28 |
18 |
41 |
|
| Mean (SD) |
24.3 (1.2) |
24.2 (1.4) |
24.3 (1.5) |
|
| Range |
(22.0–26.6) |
(21.8–26.6) |
(21.0–26.9) |
|
| POY2 visual acuity, logMar |
|
|
|
0.127 |
| N |
28 |
18 |
41 |
|
| Mean (SD) |
0.3 (0.6) |
0.5 (0.7) |
0.5 (0.7) |
|
| Range |
(0.0–2.5) |
(−0.1–2.5) |
(−0.1–2.6) |
|
| POY2 intraocular pressure, mm Hg |
|
|
|
0.176 |
| N |
28 |
18 |
41 |
|
| Mean (SD) |
13.6 (5.5) |
12.9 (10.8) |
11.9 (4.3) |
|
| Range |
(5.0–34.0) |
(5.0–53.0) |
(6.0–24.0) |
|
| POY2 number of classes of glaucoma meds |
|
|
|
0.772 |
| N |
28 |
18 |
40 |
|
| Mean (SD) |
2.1 (1.2) |
2.0 (1.6) |
1.9 (1.4) |
|
| Range |
(0.0–4.0) |
(0.0–5.0) |
(0.0–4.0) |
|
| Postoperative year 3 (POY3) time from GDD surgery, mo |
|
|
|
0.438 |
| N |
19 |
10 |
26 |
|
| Mean (SD) |
36.2 (1.1) |
36.5 (1.5) |
36.5 (1.0) |
|
| Range |
(33.9–37.7) |
(33.6–37.9) |
(34.3–38.1) |
|
| POY3 visual acuity, logMar |
|
|
|
0.116 |
| N |
19 |
10 |
26 |
|
| Mean (SD) |
0.3 (0.7) |
0.5 (0.8) |
0.6 (0.8) |
|
| Range |
(0.0–2.5) |
(0.0–2.6) |
(−0.1–2.6) |
|
| POY3 intraocular pressure, mm Hg |
|
|
|
0.106 |
| N |
18 |
9 |
25 |
|
| Mean (SD) |
10.9 (2.9) |
18.9 (18.6) |
11.4 (6.4) |
|
| Range |
(7.0–18.0) |
(9.0–68.0) |
(2.0–27.0) |
|
| POY3 number of classes of glaucoma meds |
|
|
|
0.196 |
| N |
19 |
10 |
25 |
|
| Mean (SD) |
1.7 (0.9) |
2.6 (1.6) |
1.6 (1.4) |
|
| Range |
(0.0–3.0) |
(0.0–4.0) |
(0.0–4.0) |
|
| Last visit time from GDD surgery, mo |
|
|
|
0.312 |
| N |
43 |
36 |
78 |
|
| Mean (SD) |
42.7 (33.0) |
29.9 (16.6) |
38.3 (36.1) |
|
| Range |
(7.3–159.3) |
(3.3–78.9) |
(1.9–185.7) |
|
| Last visual acuity, logMar |
|
|
|
0.525 |
| N |
43 |
36 |
78 |
|
| Mean (SD) |
0.4 (0.5) |
0.6 (0.8) |
0.5 (0.6) |
|
| Range |
(−0.1, 2.6) |
(0.0–2.6) |
(0.0–2.6) |
|
| Last intraocular pressure, mm Hg |
|
|
|
0.743 |
| N |
42 |
36 |
77 |
|
| Mean (SD) |
11.5 (3.2) |
12.7 (9.9) |
12.4 (5.5) |
|
| Range |
(5.0–20.0) |
(4.0–65.0) |
(2.0–35.0) |
|
| Last number of classes of glaucoma meds |
|
|
|
0.678 |
| N |
43 |
36 |
78 |
|
| Mean (SD) |
1.7 (1.1) |
2.0 (1.3) |
1.8 (1.3) |
|
| Range |
(0.0–3.0) |
(0.0–5.0) |
(0.0–5.0) |
|
*Kruskal Wallis.
Pairwise P values reflect the Bonferroni correction for multiple comparisons.
B250 indicates Baerveldt 250; B350, Baerveldt 350; GDD, glaucoma drainage device.
;)
FIGURE 1: Mean VA over 3 years of follow-up. Error bars represent SD. B250 indicates Baerveldt 250; B350, Baerveldt 350; VA, visual acuity.
FIGURE 2: Mean IOP over 3 years of follow-up. Error bars represent SD. B250 indicates Baerveldt 250; B350, Baerveldt 350; IOP, intraocular pressure.
FIGURE 3: Mean number of classes of glaucoma medications over 3 years of follow-up. Error bars represent SD. B250 indicates Baerveldt 250; B350, Baerveldt 350.
Surgical Success
At 3 years after the GDD surgeries, 10/43 (23.3%) FP7, 11/36 (30.6%) B250, and 32/78 (41.0%) B350 eyes had met the surgical failure criteria (Table 3, Fig. 4, P=0.127), while complete success was achieved in 18/43 (41.9%) FP7, 13/36 (36.1%) B250, and 24/78 (30.8%) B350 eyes (P=0.467). Among eyes that met the failure criteria (Table 4), the first criterion most of them met was IOP reduction <20% from baseline on 2 consecutive months postoperatively: 3/10 (30.0%) FP7, 8/11 (63.6%) B250, and 13/32 (40.6%) B350 eyes (P=0.313). The second and third most common reasons for treatment failure were the need for additional glaucoma surgery (P=0.481) and IOP elevation to >21 mm Hg (P=0.257), respectively.
TABLE 3 -
Success Analysis 3 Years After Glaucoma Drainage Device Surgery
|
FP7 (N=43) |
B250 (N=36) |
B350 (N=78) |
Total (N=157) |
P
*
|
| Surgical success, n |
43 |
36 |
78 |
157 |
|
| Failure, n (%) |
10 (23.3) |
11 (30.6) |
32 (41.0) |
53 (33.8) |
0.127 |
| Partial success, n (%) |
15 (34.9) |
12 (33.3) |
22 (28.2) |
49 (31.2) |
0.714 |
| Complete success, n (%) |
18 (41.9) |
13 (36.1) |
24 (30.8) |
55 (35.0) |
0.467 |
| Clinical success, n |
18 |
11 |
25 |
54 |
|
| Target IOP range met, n (%) |
17 (94.4) |
9 (81.8) |
21 (84.0) |
47 (87.0) |
0.510 |
| Missing data, n |
25 |
25 |
53 |
103 |
|
| No additional glaucoma surgery, n (%) |
39 (90.7) |
34 (94.4) |
66 (84.6) |
139 (88.5) |
0.270 |
| Failure, n (%) |
0 |
1 (9.1) |
1 (4.0) |
2 (3.7) |
0.451 |
| Success, n (%) |
15 (83.3) |
9 (81.8) |
17 (68.0) |
41 (75.9) |
0.447 |
*χ2 test.
B250 indicates Baerveldt 250; B350, Baerveldt 350; IOP, intraocular pressure.
FIGURE 4: Kaplan-Meier plot for surgical failure over 3 years after glaucoma drainage device surgery. B250 indicates Baerveldt 250; B350, Baerveldt 350.
TABLE 4 -
Reasons for Surgical Failure
|
FP7 (N=10) |
B250 (N=11) |
B350 (N=32) |
Total (N=53) |
P
*
|
| IOP ≤5, n (%) |
2 (20.0) |
2 (18.2) |
7 (21.9) |
11 (20.8) |
1.000 |
| IOP >21, n (%) |
4 (40.0) |
1 (9.1) |
8 (25.0) |
13 (24.5) |
0.257 |
| IOP reduction <20% baseline, n (%) |
3 (30.0) |
7 (63.6) |
13 (40.6) |
23 (43.4) |
0.313 |
| Additional glaucoma surgery, n (%) |
4 (40.0) |
2 (18.2) |
12 (37.5) |
18 (34.0) |
0.481 |
| GDD removal, n (%) |
1 (10.0) |
0 |
0 |
1 (1.9) |
0.189 |
| Loss of light perception, n (%) |
0 |
1 (9.1) |
1 (3.1) |
2 (3.8) |
0.640 |
*For patients with >1 reason for treatment failure, they were included under the first failure criterion met. Fisher exact test used.
B250 indicates Baerveldt 250; B350, Baerveldt 350; GDD, glaucoma drainage device; IOP, intraocular pressure.
Clinical Success
At 3 years after the GDD surgeries, 15/18 (83.3%) FP7, 9/11 (81.8%) B250, and 17/25 (68.0%) B350 eyes had achieved clinical success (P=0.447, Table 3). There were no significant differences in the rates at which the target IOP ranges were met among the GDD groups (P=0.510). Additional glaucoma surgery was required in 4/10 (40.0%) FP7, 2/11 (18.2%) and 12/32 (37.5%), B350 eyes (P=0.481, Table 4). Among eyes that needed additional glaucoma surgery, an additional GDD was the most common surgery (P=0.150, Table 5).
TABLE 5 -
Additional Glaucoma Surgeries
|
FP7 (N=43) |
B250 (N=36) |
B350 (N=78) |
Total (N=157) |
P
*
|
| Additional glaucoma procedure, n (%) |
4 (9.3) |
2 (5.6) |
12 (15.4) |
18 (11.5) |
0.270 |
| GDD |
2 (4.7) |
0 |
7 (9.0) |
9 (5.7) |
0.150 |
| Trabeculectomy |
1 (2.3) |
1 (2.8) |
2 (2.6) |
4 (2.5) |
0.992 |
| Trabeculotomy |
0 |
0 |
2 (2.6) |
2 (1.3) |
0.358 |
| Cyclodestruction |
1 (2.3) |
1 (2.8) |
1 (1.3) |
3 (1.9) |
0.840 |
*χ2.
B250 indicates Baerveldt 250; B350, Baerveldt 350; GDD, glaucoma drainage device.
Complications and Interventions
Postoperative complications during 3 years of follow-up included hemorrhage (hyphema or vitreous hemorrhage), corneal decompensation, Seidel positivity, low or elevated IOP, inflammation, tube complications, or diplopia (Table 6). Rates of all the complication types were similar among all the GDD groups (P=0.119). Rates of intervention to address complications were also similar among the GDD groups (P=1.00, Table 7), with the most common intervention being glaucoma medications.
TABLE 6 -
Postoperative
Complications 3 Years After Glaucoma Drainage Device Surgery
|
FP7 (N=43) |
B250 (N=36) |
B350 (N=78) |
Total (N=157) |
P
*
|
| Any postoperative complication, n (%) |
20 (46.5) |
14 (38.9) |
46 (59.0) |
80 (51.0) |
0.119 |
| Hemorrhage, n (%) |
| Hyphema |
6 (14.0) |
6 (16.7) |
11 (14.1) |
23 (14.6) |
0.915 |
| Vitreous hemorrhage |
0 |
0 |
2 (2.6) |
2 (1.3) |
0.726 |
| Corneal decompensation, n (%) |
| Low endothelial cell density |
0 |
0 |
1 (1.3) |
1 (0.6) |
1.000 |
| Corneal edema |
2 (4.7) |
0 |
3 (3.8) |
5 (3.2) |
0.602 |
| Corneal graft failure |
0 (0.0) |
0 |
3 (3.8) |
3 (1.9) |
0.434 |
| Corneal graft decentration |
0 |
0 |
1 (1.3) |
1 (0.6) |
1.000 |
| Dellen |
1 (2.3) |
0 |
0 |
1 (0.6) |
0.503 |
| Seidel positivity, n (%) |
0 |
2 (5.6) |
3 (3.8) |
5 (3.2) |
0.359 |
| Low intraocular pressures, n (%) |
| Hypotony |
1 (2.3) |
2 (5.6) |
6 (7.7) |
9 (5.7) |
0.604 |
| Shallow AC |
1 (2.3) |
0 |
0 |
1 (0.6) |
0.503 |
| Choroidal effusion |
3 (7.0) |
2 (5.6) |
6 (7.7) |
11 (7.0) |
1.000 |
| Elevated intraocular pressures, n (%) |
1 (2.3) |
3 (8.3) |
11 (14.1) |
15 (9.6) |
0.101 |
| Inflammation, n (%) |
| Anterior uveitis |
1 (2.3) |
0 |
3 (3.8) |
4 (2.5) |
0.809 |
| Macular edema |
0 |
0 |
2 (2.6) |
2 (1.3) |
0.726 |
| Tube complications, n (%) |
| Tube occlusion |
2 (4.7) |
2 (5.6) |
3 (3.8) |
7 (4.5) |
0.886 |
| Tube erosion |
2 (4.7) |
0 |
0 (0.0) |
2 (1.3) |
0.125 |
| Tube malposition |
1 (2.3) |
0 |
4 (5.1) |
5 (3.2) |
0.510 |
| Diplopia, n (%) |
9 (20.9) |
4 (11.1) |
9 (11.5) |
22 (14.0) |
0.338 |
*Fisher Exact.
B250 indicates Baerveldt 250; B350, Baerveldt 350.
TABLE 7 -
Interventions for Postoperative
Complications 3 Years After Glaucoma Drainage Device Surgery
|
FP7 (N=20) |
B250 (N=14) |
B350 (N=32) |
Total (N=77) |
P
*
|
| Any intervention, n (%) |
14 (70.0) |
10 (71.4) |
33 (71.7) |
57 (71.3) |
1.000 |
| Glaucoma medication, n (%) |
5 (25.0) |
4 (28.6) |
9 (19.6) |
18 (22.5) |
0.712 |
| Tube revision, n (%) |
| Tube repositioning |
1 (5.0) |
0 |
5 (10.9) |
6 (7.5) |
0.518 |
| Tube probing/opening |
2 (10.0) |
0 (0.0) |
1 (2.2) |
3 (3.8) |
0.230 |
| Tube occlusion |
0 |
0 |
2 (4.3) |
2 (2.5) |
1.000 |
| Tube patch graft |
0 |
0 |
0 |
0 |
NA |
| Tube extension |
0 |
0 |
2 (4.3) |
2 (2.5) |
1.000 |
| Tube ligature removal |
0 |
0 |
0 |
0 |
NA |
| YAG for occluded tube |
1 (5.0) |
0 |
1 (2.2) |
2 (2.5) |
0.672 |
| AC reformation, n (%) |
1 (5.0) |
0 |
1 (2.2) |
2 (2.5) |
0.672 |
| AC tap, n (%) |
0 |
1 (7.1) |
1 (2.2) |
2 (2.5) |
0.381 |
| Wound suture for Seidel positivity, n (%) |
0 |
2 (14.3) |
3 (6.5) |
5 (6.3) |
0.280 |
| Bandage contact lens, n (%) |
0 |
0 |
1 (2.2) |
1 (1.3) |
1.000 |
| Endothelial graft, n (%) |
1 (5.0) |
0 |
5 (10.9) |
6 (7.5) |
0.518 |
| Prisms, n (%) |
5 (25.0) |
1 (7.1) |
5 (10.9) |
11 (13.8) |
0.325 |
| Strabismus surgery, n (%) |
1 (5.0) |
0 |
1 (2.2) |
2 (2.5) |
0.672 |
| GDD removal, n (%) |
1 (5.0) |
0 |
0 |
1 (1.3) |
0.425 |
| Selective laser trabeculoplasty, n (%) |
0 |
0 |
1 (2.2) |
1 (1.3) |
1.000 |
| Laser peripheral iridotomy, n (%) |
0 |
1 (7.1) |
0 |
1 (1.3) |
0.175 |
*Fisher exact.
B250 indicates Baerveldt 250; B350, Baerveldt 350; NA, not applicable.
DISCUSSION
In this direct comparison of the 3 most commonly used GDDs, FP7, B250, and B350, this study found remarkably similar clinical outcomes in terms of both surgical and clinical success rates. Three years after the GDD surgeries, surgical success rates ranged from 30.8% to 41.9%, and clinical success rates ranged from 68.0% to 83.3%.
There have been a multitude of studies comparing different GDDs in terms of their surgical success rates, but to our knowledge, this is the first study comparing the 3 common GDDs’ surgical and clinical success rates. For example, there have been retrospective comparative studies16,17 and meta-analyses18,19 comparing Ahmed and Baerveldt tubes without distinction between B250 and B350 GDDs. Some compare Ahmed to B350 only.20–22 As summarized in Table 1 by Wang and colleagues, 2015, there have been no direct comparison of FP7 with B250 and B350 separately. Complete/partial success and failure definitions have also varied among the studies. We, therefore. found it difficult to extrapolate findings from these prior studies and believe our current study will help providers better compare the 3 GDDs using the ABC definitions of surgical success/failure. In addition, none of these prior studies evaluated clinical success/failure using individual target IOP ranges as a criterion, which may be more relevant when counseling each patient.
In recent years, the ABC and the AVB Studies have been the largest multicenter randomized clinical trials, reporting 5-year cumulative surgical success rates of 51% in the FP7 group and 63% in the B350 group.9 At 3 years, the ABC study reported complete surgical success rates of 20% and 33% in the FP7 and B350 groups, respectively.23 In contrast, the AVB study reported 4% and 11% complete surgical success rates in their FP7 and B350 groups.24 This study found 3-year complete surgical success rates of 41.9% in the FP7 group, 36.1% in the B250 group, and 30.8% in the B350 group.
One main reason for the wide disparity in complete success rates may be differences in its definition across studies. For complete success, the ABC study required IOPs ≤21 mm Hg, >5 mm Hg, a reduction≥20% from baseline and no glaucoma medications used.25 The AVB study required IOP 5–18 mm Hg, a reduction≥20% from baseline at every visit after 3 months, no glaucoma medications, no vision-threatening complications related to the implant/surgery, no additional glaucoma surgery or laser procedures (except for procedures performed at the slit-lamp like suture removal, paracentesis), and no doubling of the logMAR.26 In this study, the ABC definition was applied. IOP <5 mm Hg was included in the definition of surgical failure, but hypotony as reported in Table 6 was based on the surgeons’ clinical exams, so eyes without clinically significant hypotony (hypotony maculopathy, choroidal effusions, shallow anterior chamber, for example) may not have been classified as having the complication.
Neither the ABC nor the AVB studies incorporated each eye’s target IOP ranges in their definitions of success, although reaching the individualized IOP target range is arguably one of the most important clinical indicators of a successful intervention.9 In this study, target IOP ranges were met in 94.4% FP7, 81.8% B250, and 84.0% B350 eyes 3 years postoperatively.
The need for additional glaucoma surgery is a second important clinical indicator of treatment failure, which was reported by the ABC and AVB studies. The ABC study reported 3-year reoperation rates of 14.5% in the FP7 group and 7.6% in the B350 group,23 while the AVB study reported additional glaucoma surgeries in 11% FP7 and 6% B350 eyes.24 This study found that additional glaucoma surgery was required in 9.3% FP7, 5.6% B250, and 15.4% B350 eyes. The discrepancies in the findings may, in part, be due to this study’s limitations.
Our study was limited by its retrospective design, the racial homogeneity of the study population, variable surgeon preferences for the different GDD types, and selection bias. Postoperative enrollment allowed for larger sample sizes, but resulted in inconsistent timing and availability of postoperative data. Severity of glaucoma, for instance, could not be consistently determined based on optical coherence tomography or visual field analyses due to variable timing of the tests relative to the GDD surgeries. It is possible that differences in the severity of glaucoma and clinical pathology may have contributed to the different success rates, and it would be an important area of investigation for a future study. In additiona, with 95% of the study population identifying themselves as White, it may be difficult to extrapolate these results to other non-White populations. In addition, most of the surgeons at our institution preferred B350 unless there was an indication for FP7 (need for immediate postoperative lowering of IOP) or B250 (concern for postoperative hypotony, or a tighter orbit or scar tissue limiting space for the larger B350 plate). This limited our enrollment of FP7 and B250 patients. Each GDD group had at least 2 surgeons represented, however, and there were no significant differences in median VA or glaucoma types between surgeons. All surgeons at our institution also had similar surgical techniques in suturing the GDD plates sub-Tenons ~10 mm posterior to the limbus and tucking the wings of B350 plates under the superior and lateral rectus muscles while placing B250 and FP7 plates between the 2 muscles. Lastly, our study design was susceptible to selection bias as patients with worse postoperative outcomes were likely seen more frequently, although this bias would be expected to have affected all the treatment groups.
In conclusion, there was no clear superiority among the 3 GDDs in terms of surgical or clinical success rates at 3 years after GDD surgery. Prospective data, larger sample sizes and longer follow-up would aid in future comparisons of GDDs as they continue to evolve in design. Future directions may also include an evaluation of the rate of visual field progression postoperatively as a marker of clinical failure.
REFERENCES
1. Vinod K, Gedde SJ, Feuer WJ, et al. Practice preferences for glaucoma surgery: a survey of the American Glaucoma Society. J Glaucoma. 2017;26:687–693.
2. Schmier JK, Covert DW, Lau EC, et al. Trends in annual medicare expenditures for glaucoma surgical procedures from 1997 to 2006. Arch Ophthalmol. 2009;127:900–905.
3. Ramulu PY, Corcoran KJ, Corcoran SL, et al. Utilization of various glaucoma surgeries and procedures in medicare beneficiaries from 1995 to 2004. Ophthalmology. 2007;114:2265–2270.
4. Arora KS, Robin AL, Corcoran KJ, et al. Use of various glaucoma surgeries and procedures in medicare beneficiaries from 1994 to 2012. Ophthalmology. 2015;122:1615–1624.
5. Gedde SJ, Herndon LW, Brandt JD, et al. Postoperative
complications in the Tube Versus Trabeculectomy (TVT) study during five years of follow-up. Am J Ophthalmol. 2012;153:804–814e1.
6. Gedde SJ, Schiffman JC, Feuer WJ, et al. Treatment outcomes in the Tube Versus Trabeculectomy (TVT) study after five years of follow-up. Am J Ophthalmol. 2012;153:789–803.
7. Christakis PG, Kalenak JW, Tsai JC, et al. The Ahmed Versus Baerveldt Study: five-year treatment outcomes. Ophthalmology. 2016;123:2093–2102.
8. Budenz DL, Barton K, Gedde SJ, et al. Five-year treatment outcomes in the Ahmed Baerveldt comparison study. Ophthalmology. 2015;122:308–316.
9. Christakis PG, Zhang D, Budenz DL, et al. Five-year pooled data analysis of the Ahmed Baerveldt Comparison Study and the Ahmed Versus Baerveldt Study. Am J Ophthalmol. 2017;176:118–126.
10. Siegner SW, Netland PA, Urban RC Jr, et al. Clinical experience with the Baerveldt glaucoma drainage implant. Ophthalmology. 1995;102:1298–1307.
11. Goulet RJ III, Phan AD, Cantor LB, et al. Efficacy of the Ahmed S2 glaucoma valve compared with the Baerveldt 250-mm
2 glaucoma implant. Ophthalmology. 2008;115:1141–1147.
12. Allan EJ, Khaimi MA, Jones JM, et al. Long-term efficacy of the Baerveldt 250 mm
2 compared with the Baerveldt 350 mm
2 implant. Ophthalmology. 2015;122:486–493.
13. Meyer AM, Rodgers CD, Zou B, et al. Retrospective comparison of intermediate-term efficacy of 350 mm(
2) glaucoma drainage implants and medium-sized 230-250 mm(
2) implants. J Curr Glaucoma Pract. 2017;11:8–15.
14. Rodgers CD, Meyer AM, Sherwood MB. Relationship between glaucoma drainage device size and intraocular pressure control: does size matter? J Curr Glaucoma Pract. 2017;11:1–2.
15. Sun PY, Leske DA, Holmes JM, et al. Diplopia in medically and surgically treated patients with glaucoma. Ophthalmology. 2017;124:257–262.
16. Sinha S, Ganjei AY, McWatters Z, et al. Ahmed versus Baerveldt glaucoma drainage device in uveitic glaucoma: a retrospective comparative study. J Glaucoma. 2020;29:750–755.
17. Koentjoro SL, Rtini W, Soebijantoro I, et al. Comparison of
complications after Ahmed versus Baerveldt implant in glaucoma patients: one year follow-up. Int J Ophthalmol. 2020;13:1908–1914.
18. Wang S, Gao X, Qian N. The Ahmed shunt versus the Baerveldt shunt for refractory glaucoma: a meta-analysis. BMC Ophthalmol. 2016;16:83.
19. Wang Y, Wang P, Zeng C, et al. Comparison of the Ahmed glaucoma valve with the Baerveldt glaucoma implant: a meta-analysis. BMC Ophthalmol. 2015;15:132.
20. Moschos MM, Nitoda E, Gouliopoulos N, et al. The choice of drainage device in complicated glaucomas: comparing Ahmed and Baerveldt implants
In Vivo. 2019;33:911–916.
21. Yadgarov A, Liu D, Crane ES, et al. Surgical outcomes of Ahmed or Baerveldt tube shunt implantation for medically uncontrolled traumatic glaucoma. J Curr Glaucoma Pract. 2017;11:16–21.
22. Syed HM, Law SK, Nam SH, et al. Baerveldt-350 implant versus Ahmed valve for refractory glaucoma: a case-controlled comparison. J Glaucoma. 2004;13:38–45.
23. Barton K, Feuer WJ, Budenz DL, et al. Three-year treatment outcomes in the Ahmed Baerveldt comparison study. Ophthalmology. 2014;121:1547–1557.e1.
24. Christakis PG, Tsai JC, Kalenak JW, et al. The Ahmed versus Baerveldt study: three-year treatment outcomes. Ophthalmology. 2013;120:2232–2240.
25. Barton K, Gedde SJ, Budenz DL, et al. Ahmed Baerveldt Comparison Study Group. The Ahmed Baerveldt Comparison Study methodology, baseline patient characteristics, and intraoperative
complications. Ophthalmology. 2011;118:435–442.
26. Christakis PG, Tsai JC, Zurakowski D, et al. The Ahmed Versus Baerveldt study: design, baseline patient characteristics, and intraoperative
complications. Ophthalmology. 2011;118:2172–2179.
