Risk Factors for Tube Shunt Exposure: A Matched Case-Control Study
Table 1
Demographics/preoperative glaucoma patient characteristics and tube shunt implantation parameters.
Variable
Cases
Controls
valuea
Center, no. of cases/controls (%)
1.000
BPEI
24 (58.5)
46 (57.5)
UTH
17 (41.5)
34 (42.5)
Demographics
Sex (female, %)b
25 (61.0)
48 (60.0)
1.000
Race/ethnicity, no. of patients (%)
0.015c
White
12 (29.3)
32 (40.0)
Black
9 (22.0)
29 (36.3)
Hispanic
20 (48.8)
17 (21.3)
Asian
0 (0.0)
2 (2.5)
Age, mean years (SD)
64.2 (19.1)
63.6 (20.2)
0.8713
Comorbid systemic diseases
Diabetes, no. of eyes (%)
12 (29.3)
18 (22.5)
0.5054
Hypertension, no. of eyes (%)
17 (41.5)
31 (38.8)
0.8452
Baseline ocular information (before shunt implantation)
Type of glaucoma, no. of eyes (%)
0.0235c
Primary open angle glaucoma
11 (26.8)
38 (47.5)
Neovascular glaucoma (NVG)
9 (22.0)
6 (7.5)
Others
21 (51.2)
36 (45.0)
Preoperative intraocular pressure, mean mmHg (SD)
30.8 (11.2)
29.9 (10.1)
0.6573
No. of IOP-lowering medications, mean (SD)
2.1 (1.0)
2.3 (1.1)
0.4369
Previous trabeculectomy, no. of eyes (%)
21 (51.2)
26 (32.9)d
0.0753
Previous tube shunt implantation, no. of eyes (%)
4 (9.8)
3 (3.3)
0.2285
Previous laser procedure (ALT), no. of eyes (%)
3 (7.3)
6 (7.7)e
1.000
Previous PK/PKP, no. of eyes (%)
4 (9.8)
6 (7.5)
0.7324
Previous PRP/EL, no. of eyes (%)
15 (36.6)
6 (7.7)e
0.0002c
Previous vitrectomy, no. of eyes (%)
9 (22.0)
9 (11.3)
0.1755
Previous ocular surgeries, no. of eyes 3 or more (%)
24 (58.5)
22 (27.5)
0.0014c
Tube shunt implantation parameters
Type of shunt device, no. of Baerveldt (%)
40 (97.6)
77 (96.3)
1.000
Device location, no. of superotemporal (%)
40 (97.6)
73 (91.3)
0.2633
Tube entry site, no. of anterior chambers (%)
28 (92.7)
74 (92.5)
1.000
Type of patch graft used, no. of scleral patch grafts (%)
29 (70.7)
26 (62.5)
0.3416
Combined surgery, no. of eyes (%)
16 (39.0)
19 (19.8)
0.0928
Combined with cataract, no. of eyes (%)
6 (14.6)
12 (15.0)
1.000
Combined with PKP, no. of eyes (%)
2 (4.9)
1 (1.3)
0.2648
Combined with vitrectomy, no. of eyes (%)
9 (13.0)
10 (12.5)
0.1945
BPEI: Bascom Palmer Eye Institute; UTH: The University of Texas Medical School at Houston; NVG: neovascular glaucoma; PKP: penetrating keratoplasty; ALT: argon laser trabeculoplasty; PK: penetrating keratectomy; PRP: panretinal photocoagulation; EL: endolaser; SD: standard deviation; No.: number.
aObtained from two-sample -test for continuous variables and Fisher exact test for discrete variables.
bSex was used to match cases to controls.
cStatistically significant, .
dOne missing observation.
eTwo missing observations. Note: 5 eyes combined with both cataract and vitrectomy (1 case, 4 controls).
