Eye characteristics
A total of 325 eyes of 261 patients were observed in the study, including 116 males (44.4%) and 145 females (55.6%). The mean follow-up time was 22 ± 12 months, ranging from 12 to 57 months. The average age was 59.3 ± 12.8 (19-90) years old, and 189 (58.2%) patients were over 60 years old. PACG was the main type of glaucoma, which accounted for 64.6% of patients. The mean preoperative IOP was 32.9 ± 12.0 mmHg, and the mean number of topical IOP-lowering medications before surgery was 3.0 ± 0.9. Of patients, 245 (75.4%) underwent trabeculectomy alone, and 80 (24.6%) received trabeculectomy combined with cataract surgery. The demographic characteristics of the patients and preoperative ocular characteristics are presented in Table 1. Information about visual field MD was unavailable in 40 cases.
Table 1 Demographic and ocular characteristics of patients with trabeculectomy at baseline
Gender, no. (%)
|
|
Female
|
145 (55.6)
|
Male
|
116 (44.4)
|
Age (yrs), Mean ± SD
|
59.3 ± 12.8
|
< 60, no. (%)
|
136 (41.8)
|
≥ 60, no. (%)
|
189 (58.2)
|
Hypertension, no. (%)
|
|
Yes
|
54 (16.6)
|
No
|
271 (83.4)
|
Diagnosis, no. (%)
|
|
PACG
|
210 (64.6)
|
POAG
|
97 (29.8)
|
SG
|
10 (3.1)
|
CG
|
8 (2.5)
|
BCVA (logMAR), Mean ± SD
|
0.77 ± 0.94
|
≤ 1, no. (%)
|
254 (78.2)
|
> 1, no. (%)
|
71 (21.8)
|
IOP (mmHg), Mean ± SD
|
32.9 ± 12.0
|
Medications, Mean ± SD
|
3.0 ± 0.9
|
Visual filed MD (dB), Mean ± SD
|
-19.73 ± 10.03
|
> -15, no. (%)
|
100 (30.8)
|
≤ -15, no. (%)
|
185 (57.0)
|
Missing data, no. (%)
|
40 (12.2)
|
Preoperative C/D, Mean ± SD
|
0.8 ± 0.2
|
Surgery type, no. (%)
|
|
Trabeculectomy
|
245 (75.4)
|
Phacotrabeculectomy
|
80 (24.6)
|
PACG, primary angle-closure glaucoma; POAG, primary open angle glaucoma; SG, secondary glaucoma; CG, congenital glaucoma; BCVA, best corrected visual acuity; logMAR, logarithm of the minimal angle of resolution; IOP, intraocular pressure; SD, standard deviation; MD, mean deviation; dB, Decibels; C/D, vertical cup to disc ratio.
Surgical outcomes and success rate
The IOP and the number of topical IOP-lowering medications at each follow-up time are shown in Table 2. The mean IOP and glaucoma medications were significantly decreased from 32.9 ± 12.0 mmHg to 16.4 ± 5.7 mmHg (P<0.0001) and 3.0 ± 0.9 to 0.9 ± 1.0 (P<0.0001), respectively, at 3-year follow-up. The IOP values and the number of topical medications were consistently lower than those observed at baseline throughout the follow-up period.
Table 2 IOP and the number of glaucoma medications for patients at baseline and follow-up
Follow-up
|
IOP (mmHg)
|
P value
|
No. of medications
|
P value
|
Baseline
|
32.9 ± 12.0
|
|
3.0 ± 0.9
|
|
1 month
|
14.2 ± 6.3
|
< 0.0001
|
0.1 ± 0.4
|
< 0.0001
|
3 months
|
14.4 ± 5.2
|
< 0.0001
|
0.2 ± 0.5
|
< 0.0001
|
6 months
|
14.9 ± 5.5
|
< 0.0001
|
0.3 ± 0.5
|
< 0.0001
|
12 months
|
14.2 ± 4.3
|
< 0.0001
|
0.3 ± 0.6
|
< 0.0001
|
24 months
|
16.0 ± 5.3
|
< 0.0001
|
0.6 ± 0.9
|
< 0.0001
|
36 months
|
16.4 ± 5.7
|
< 0.0001
|
0.9 ± 1.0
|
< 0.0001
|
IOP, intraocular pressure; No., number.
The Kaplan-Meier survival plot of success rate for included patients is demonstrated in Figure 1. The cumulative complete success rate was 77.8%, 66.8% and 47.2% at 1-, 2-, and 3-year follow-up visits, respectively. The cumulative qualified success rate was 92.0%, 88.5% and 77.7% at 1-, 2-, and 3-year follow-up visits, respectively.
We compared the surgical outcomes between PACG and POAG patients (Figure 2). Before the surgery, both the IOP values and the number of medications in PACG group were higher. However, after the surgery, both IOP and the number of glaucoma medications were comparable between PACG and POAG throughout 3-year follow-up. The 3-year complete success rates of PACG and POAG were 54.6%, 46.4%, while the qualified success rates were 78.7%, 71.5%, respectively. The cumulative success rates of two groups were similar.
For PACG patients who underwent with trabeculectomy alone or phacotrabeculectomy, there was no significant difference in IOP control between the two surgical procedures. There was no significant difference with respect to IOP-lowering medications between the two surgical procedures at all follow up times except 1 month after surgery. The success rates of two surgical procedures were comparable (Figure 3).
Visual acuity and visual field test
The changes of BCVA (logMAR) and visual field MD are shown in Table 3. The mean BCVA (logMAR) was 0.77 ± 0.94 before surgery and 0.67 ± 0.83 at the last follow-up. There was no significant difference between baseline and last follow-up (P=0.14). At the last follow-up, the mean visual field MD was -16.80 ± 11.47 dB, which was slightly improved compared with that at baseline (P=0.04).
Table 3 Visual acuity and visual field results at the last follow-up visit.
|
|
P value
|
BCVA (logMAR), mean ± SD
|
|
|
Baseline (n = 325)
|
0.77 ± 0.94
|
0.14
|
Last follow-up (n = 325)
|
0.67 ± 0.83
|
MD of VF (dB), mean ± SD
|
|
|
Baseline (n = 285)
|
-19.73 ± 10.03
|
0.04*
|
Last follow-up (n = 66)
|
-16.80 ± 11.47
|
BCVA, best corrected visual acuity; logMAR, logarithm of the minimal angle of resolution; SD, standard deviation; MD, mean deviation; VF, visual field; dB, Decibels.
*Not all patients at baseline returned for perimetry follow up
Postoperative complications
In our study, a total of 62 (19.1%) eyes developed postoperative complications in the follow up period. Of these, 33 (10.2%) had encapsulated bleb, 10 (3.1%) had shallow anterior chamber, 5 (1.5%) had wound leak, and 4 (1.2%) had malignant glaucoma. Postoperative complications during follow-up visits are displayed in Table 4. Encapsulated bleb was treated with massage, needling, or antifibrotic injection based on surgeon’s clinical judgement.
Table 4 Postoperative complications during follow-up visits.
Complications
|
n (%)
|
Encapsulated bleb
|
33 (10.2)
|
Shallow anterior chamber
|
10 (3.1)
|
Hyphema
|
8 (2.5)
|
Wound leak
|
5 (1.5)
|
Malignant glaucoma
|
4 (1.2)
|
Choroidal effusion
|
2 (0.6)
|
Total
|
62 (19.1)
|
Risk factors for surgical failure
The risk factors for surgical failure were investigated using Cox proportional hazard analysis (see Table 5). Hypertension (HR=1.904, P=0.011), encapsulated bleb (HR=2.756, P<0.001), and preoperative more topical medications (HR=2.475, P=0.008) were associated with a higher risk of surgical failure.
Table 5 Cox proportional hazard ratio of risk factors for failure
Factor
|
Complete success
|
Qualified success
|
HR (95%CI)
|
P value
|
HR (95%CI)
|
P value
|
Gender
|
1.265 (0.808 - 1.981)
|
0.304
|
0.985 (0.479 - 2.206)
|
0.966
|
Age
|
0.971 (0.602 - 1.565)
|
0.902
|
1.326 (0.632 - 2.781)
|
0.455
|
Hypertension
|
1.904 (1.156 - 3.136)
|
0.011*
|
1.742 (0.815 - 3.723)
|
0.152
|
Glaucoma type
|
1.288 (0.781 - 2.123)
|
0.321
|
1.261 (0.558 - 2.850)
|
0.577
|
Preoperative medications
|
1.189 (0.767 - 1.846)
|
0.439
|
2.475 (1.267 - 4.835)
|
0.008*
|
Preoperative BCVA
|
0.771 (0.453 - 1.314)
|
0.339
|
1.491 (0.739 - 3.008)
|
0.265
|
Encapsulated bleb
|
2.756 (1.592 - 4.770)
|
< 0.001*
|
1.679 (0.662 - 4.260)
|
0.275
|
Surgery type
|
1.034 (0.628 - 1.703)
|
0.896
|
1.159 (0.550 - 2.442)
|
0.698
|
HR, hazard ratio; CI, confidence interval; BCVA, best corrected visual acuity. *, P value ≤ 0.05.