Results from a total of 80 eyes from 80 patients were analyzed. Table 1 summarizes their demographic and clinical characteristics, and the results of univariate risk-factor assessment for BGI exposure. The mean follow-up period was 26.0 ± 15.0 months, and all patients were Japanese. The mean age was 57.0 ± 23.0 years-old and the subjects included 11 children under 20-years-old (13.8%).
Table 1. Demographic characteristics of patients who had a Baerveldt glaucoma drainage implant surgery
Characteristics
|
Exposure eyes
(n=12)
|
Control eyes
(n=68)
|
P value *
|
Age (years)
|
|
|
0.93
|
Mean ± SD
|
57.4±19.8
|
56.8±24.5
|
|
Follow up period (months)
|
|
|
0.94
|
Mean ± SD
|
26.2±17.6
|
26.6±14.5
|
|
Sex
|
|
|
1.00
|
Male
|
7
|
38
|
|
Female
|
5
|
30
|
|
Eye
|
|
|
0.35
|
Right
|
9
|
40
|
|
Left
|
3
|
28
|
|
Diabetes mellitus
|
|
|
0.32
|
Yes
|
6
|
22
|
|
No
|
6
|
46
|
|
Type of glaucoma
|
|
|
0.51
|
Primary open angle
|
0
|
7
|
|
Neovascular
|
6
|
20
|
|
Secondary
|
5
|
28
|
|
Pediatric
|
1
|
12
|
|
Chronic angle closure
|
0
|
1
|
|
Previous ocular surgery
|
|
|
1.00
|
Yes
|
12
|
63
|
|
No
|
0
|
5
|
|
Previous TLE, no. of eyes
3 or more
|
|
|
0.46
|
Yes
|
4
|
15
|
|
No
|
8
|
53
|
|
Type of implant
|
|
|
0.099
|
BG 101-350/ BG 103-250
|
8
|
59
|
|
BG 102-350
|
4
|
9
|
|
implant location
|
|
|
0.84
|
Superior-temporal
|
3
|
21
|
|
Inferior-temporal
|
9
|
44
|
|
Superior-nasal
|
0
|
1
|
|
Inferior-nasal
|
0
|
2
|
|
implant location
|
|
|
0.74
|
Superior
|
3
|
22
|
|
Inferior
|
9
|
46
|
|
Tube entry site
|
|
|
0.50
|
Anterior chamber
|
3
|
24
|
|
Posterior chamber
|
5
|
32
|
|
Vitreous
|
4
|
12
|
|
Type of patch graft
|
|
|
0.095
|
Self-sclera flap
|
9
|
63
|
|
Human donor sclera
|
3
|
5
|
|
SD: standard deviation, TLE: trabeculectomy, no.: number.
* P values were obtained from two-sample t-tests for continuous variables and Fisher’s exact tests for categorical variables.
Implant exposure occurred in 12 eyes (15.0%) out of the 80 eyes. The mean period to exposure was 13.42 ±10.67 months (2-34months). In the exposure cases, a BG 101-350 or BG 103-250 implant had been used in eight cases and a BG102-350 implant was used in four. Of the eight cases in which a BG 101-350 or BG 103-250 implant was exposed, seven were tube exposures and one was a plate exposure. In the four cases with BG 102-350 implant exposure, three cases had Hoffman elbow exposure and one had a plate exposure. Thus, in most of the exposure cases, the tube or Hoffman elbow was exposed (83.3%, 10 of 12). The two patients with plate exposure each had pars plana vitrectomy after BGI surgery.
The rate of exposure for BG 102-350 was high; 4 of 13 (30.7%) among patients with that type of implant. In contrast to this, the BG 101-350 and BG 103-250 were exposed in 8 of 67 cases (11.9%). However, this difference did not reach statistical significance (p=0.099).
Table 2 lists the risk factors for implant exposure that were selected by the stepwise method of logistic regression analysis. There was a trend to BG 102-350 having a higher risk of exposure, compared with BG 101-350 and BG 103-250 (p=0.092; adjusted odds ratio (OR)=3.34; 95% confidence interval (CI), 0.82–13.58), but it did not reach statistical significance.
Table 2. Risk-factors assessment for Baerveldt glaucoma drainage implant exposure
Risk factor
|
Adjusted odds ratio
|
95% confidence interval
|
P value *
|
Type of implant
|
|
|
|
BG 102-350
|
3.34
|
0.82-13.58
|
0.092
|
BG 101-350/ BG 103-250
|
1.00
|
|
|
Previous TLE, no. of eyes
3 or more
|
|
|
|
Yes
|
1.82
|
0.14-2.14
|
0.39
|
No
|
1.00
|
|
|
TLE: trabeculectomy; no.: number.
* Logistic regression analysis
In the exposure group, neovascular glaucoma was the most common diagnosis, at 50%, followed by secondary glaucoma (41.7%) and pediatric glaucoma (8.3%). In the control group, secondary glaucoma (41.2%) was the most common diagnosis and the remaining diagnoses consisted of neovascular glaucoma (29.4%), pediatric glaucoma (17.6%), primary open angle glaucoma (10.3%) and chronic angle closure glaucoma (1.5%). Because many patients (53 of 80, 66.3%) had previously undergone glaucoma surgery, in a superior location, more than half of the devices were implanted inferiorly (56 of 80, 68.8%).
Most of the patients who were implanted with a BG 102-350 had diabetes mellitus (9 of 13, 69.2%). Tables 3 and 4 show the results of subgroup analysis of the diabetic patients. Table 3 presents the characteristics of those patients and the resultant risk factors for BGI exposure in univariate analysis. Among the patients with diabetes, the exposure rate with BG 102-350 was 44.4% (4 of 9), whereas the exposure rate with a BG 101-350 or BG 103-250 was 10.5% (2 of 19). Table 4 shows the associated risk factors for implant exposure in patients with diabetes mellitus, as selected by logistic regression analysis. The BG 102-350 had a significantly greater risk for implant exposure (p=0.038; adjusted OR =15.36; 95% CI, 1.17–202.59). Using a BG 102-350 increased the risk of exposure to about 15 times the risk with BG 101-350 and BG 103-250 in the diabetic patients.
Table 3. Univariate analysis of the risk factors for Baerveldt glaucoma drainage implant exposure in diabetic patients
Characteristics
|
Exposure eyes
(n=6)
|
Control eyes
(n=22)
|
P value *
|
Age (years)
|
|
|
0.49
|
Mean ± SD
|
60.3±12.3
|
64.6±12.2
|
|
Follow up period (months)
|
|
|
0.22
|
Mean ± SD
|
36.3±15.1
|
26.4±15.0
|
|
Sex
|
|
|
1.00
|
Male
|
4
|
13
|
|
Female
|
2
|
9
|
|
Eye
|
|
|
1.00
|
Right
|
4
|
14
|
|
Left
|
2
|
8
|
|
Type of glaucoma
|
|
|
0.23
|
Primary open angle
|
0
|
3
|
|
Neovascular
|
4
|
17
|
|
Secondary
|
2
|
2
|
|
Previous ocular surgery
|
|
|
1.00
|
Yes
|
5
|
18
|
|
No
|
1
|
4
|
|
Previous TLE, no. of eyes
3 or more
|
|
|
0.14
|
Yes
|
3
|
4
|
|
No
|
3
|
18
|
|
Type of implant
|
|
|
0.064
|
BG 101-350/ BG 103-250
|
2
|
17
|
|
BG 102-350
|
4
|
5
|
|
Implant location
|
|
|
1.00
|
Superior-temporal
|
2
|
7
|
|
Inferior-temporal
|
4
|
14
|
|
Superior-nasal
|
0
|
1
|
|
Implant location
|
|
|
1.00
|
Superior
|
2
|
8
|
|
Inferior
|
4
|
14
|
|
Tube entry site
|
|
|
0.42
|
Anterior chamber
|
0
|
3
|
|
Posterior chamber
|
2
|
11
|
|
Vitreous
|
4
|
8
|
|
SD: standard deviation, TLE: trabeculectomy, no.: number.
* P values were obtained from two-sample t-tests for continuous variables and Fisher’s exact tests for categorical variables.
Table 4. Multivariate analysis of the risk factors for Baerveldt glaucoma drainage implant exposure in the diabetic patients
Risk factor
|
Adjusted odds ratio
|
95% confidence interval
|
P value *
|
Type of implant device
|
|
|
|
BG 102-350
|
15.36
|
1.17-202.59
|
0.038 **
|
BG 101-350/ BG 103-250
|
1.00
|
|
|
Previous TLE, no. of eyes
3 or more
|
|
|
|
Yes
|
12.41
|
0.82-185.96
|
0.068
|
No
|
1.00
|
|
|
Implant location
|
|
|
|
Inferior
|
0.32
|
0.027-3.78
|
0.36
|
Superior
|
1.00
|
|
|
TLE: trabeculectomy; no.: number.
* Logistic regression analysis
** Statistically significant, P<0.05.
Cox proportional hazards regression model analysis for implant exposure in the diabetic patients is shown in Table 5. In such analyses, the use of the BG 102-350, history of 3 or more previous TLE and inferior implant location did not show a significant risk for implant exposure (BG 102-350: p=0.061, OR=5.52, 95% CI 0.92–46.99; 3 or more previous TLE: p=0.062, OR=6.01, 95% CI 0.90–49.00; inferior implant location: p=0.28, OR=0.34, 95% CI 0.05–2.79).
Table 5. Cox proportional hazard regression analysis for Baerveldt glaucoma drainage implant exposure in the diabetic patients
Risk factor
|
Odds ratio
|
95% confidence interval
|
P value *
|
Type of implant device
|
|
|
|
BG 102-350
|
5.52
|
0.92-46.99
|
0.061
|
BG 101-350/ BG 103-250
|
1.00
|
|
|
Previous TLE, no. of eyes
3 or more
|
|
|
|
Yes
|
6.01
|
0.90-49.00
|
0.062
|
No
|
1.00
|
|
|
Implant location
|
|
|
|
Inferior
|
0.34
|
0.05-2.79
|
0.28
|
Superior
|
1.00
|
|
|
TLE: trabeculectomy; no.: number.
* Cox proportional hazard regression analysis