Totally, 168 patients suffering from newly diagnosed glaucoma were identified in the four years recruiting period. Of them, 40 patients were excluded and the rest, 128 patients were included and analyzed.
Excluded cases are shown in Table 1. A greater number of cases were excluded in the exfoliation (n=25) vs. the primary open-angle glaucoma group (n=15). The most common reason for exclusion in both groups was advanced visual field damage at the beginning. This reason accounted for 60% in the exfoliation and 40% in the primary open-angle glaucoma group. Trabeculectomy was the second reason for exclusion. It accounted for 32% in exfoliation and 20% in primary open-angle glaucoma patients.
Table 1
Exclusion Criteria
Cause
|
POAG
|
EXFG
|
Advanced Visual Field damage (MD≥20 dB and/or VFI ≤ 40%)
|
6 (40%)
|
15 (60%)
|
Trabeculectomy
|
3 (20%)
|
10 (32%)
|
No reliable visual fields
|
3 (20%)
|
1 (4%)
|
Other diseases
|
3 (20%)
|
1 (4%)
|
Total
|
15 (100%)
|
27 (100%)
|
POAG: primary open-angle glaucoma, EXFG: exfoliation glaucoma, MD: mean deviation, VFI: visual field index.
Included patients were 128 subjects, of the 54 in the primary open-angle, and 74 in the exfoliation group. The baseline parameters of the included patients are shown in table 2. It's interesting to observe that visual acuity was lower in the exfoliation than the primary open-angle glaucoma group though age was not significantly different. Also, exfoliation glaucoma presented more often unilateral than bilateral (78 vs. 22%).
Another parameter that differed considerably among the groups was the IOP at the beginning of the study. The average IOP in exfoliation was 32.9 mmHg; meanwhile, it was 27.6 mmHg in the primary open-angle glaucoma patients (t-test, p<0.001).
The mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI) did not differ among the groups at the beginning of the study. No difference in the studied parameters can be explained by the fact that many patients with advanced visual field defects were excluded in the exfoliation than in the primary open-angle glaucoma group.
The continuous variables: IOP, MD, and VFI were tested for normality and homoscedasticity. All variables were normally distributed according to the Kolmogorov-Smirnov test (IOP: p=0.127; MD: p=0.244; VFI, p=0.182). Regarding homoscedasticity, the Levene’s test also showed equality of variances in all the variables (IOP, p=0.623; MD, p=0.092; VFI, p=0.067)
Table 2
Baseline demographic and clinical characteristics on the patients included in the study (n=168)
|
POAG
|
EXFG
|
Test
|
P
|
Age (years) (SD)
|
69.6 (8.69)
|
71.4 (6.39)
|
T-test
|
0.20
|
Gender (M/W) (%)
|
28/26 (52/48)
|
29/35 (45/55)
|
Chi-square
|
0.57
|
Visual acuity
(Snellen) (SD)
|
0.91 (0.11)
|
0.84 (0.21)
|
T-test
|
0.027*
|
Phakia/pseudophakia (%)
|
50/4 (92.5/7.5%)
|
60/4 (93.75/6.25%)
|
Chi-square
|
0.34
|
Bilateral/unilateral
(%)
|
37/17 (69/31%)
|
14/50 (22/78%)
|
Chi-square
|
<0.001*
|
Intraocular pressure (IOP)
(mmHg) (SD)
|
27.62 (5.4)
|
32.9 (4.81)
|
T-test
|
<0.001*
|
Mean deviation (MD) (dB) (SD)
|
-5.57 (4.83)
|
-5.65 (4.52)
|
T-test
|
0.92
|
Pattern deviation (PSD) (dB) (SD)
|
5.10 (3.81)
|
4.41 (3.14)
|
T-test
|
0.28
|
Visual field index (VFI) (%) (SD)
|
87.49 (12.45)
|
87.65 (12.65)
|
T-test
|
0.94
|
POAG: primary open-angle glaucoma, EXFG: exfoliation glaucoma.
(*) = Significant values.
The results of the study after three years follow-up are shown in table 3. The difference in the mean deviation (MD) between the beginning and end of the study (3 years follow-up) was calculated for both groups. The MD difference values were higher in the exfoliation (3.17 dB) than in the primary open (1.25 dB) glaucoma group. The difference between groups was significant (t-test, p=<0.001).
The difference in VFI was calculated for the three years follow-up period. The difference was higher in the exfoliation (7.65%) than in the primary open (1.90%) glaucoma group. The difference was statistically significant (t-test, p=<0.001). The device also automatically gave a calculation of VFI deterioration/year (Rate of progression/year). The decrease of VFI/year was 2.17% for exfoliation and 0.54% for the primary open glaucoma group. The difference was also statistically significant (t-test, p=<0.001).
Regarding the proportion of cases that showed progression or not in the trend-based (VFI) showed significant progress in 50% of exfoliation and 15% of primary open glaucoma. The difference was significant (Chi-square, p=<0.001). Similar results were found when checking for the event analysis strategy, guided progression analysis (GPA). Using the GPA, 58% showed progression in the exfoliation, and 13% in the primary open glaucoma group. The difference was significant (Chi-square, p=<0.001).
The average number of medications used at the end of the study was higher in the exfoliation (2.80) than in the primary open (1.75) glaucoma group. The difference was statistically significant (t-test, p=<0.001). The number of SLT treatments performed was also higher in the exfoliation (19%) than in the primary open (4%) glaucoma group. The difference was significant (Chi-square, p=<0.005).
Table 3. Results after three years follow-up.
|
POAG
|
EXFG
|
Test
|
P-value
|
Average difference MD in 3 years (dB) (SD)
|
1.25 (1.63)
|
3.17 (2.26)
|
T-test
|
P=<0.001*
|
Average difference in VFI in 3 years
(%) (SD)
|
1.90 (1.45)
|
7.66 (5.68)
|
T-test
|
P=<0.001*
|
Average rate of progression VFI
(%/year) (SD)
|
-0.54 (1.07)
|
-2.17 (2.08)
|
T-test
|
P=<0.001*
|
Progress/No progress VFI (%)
|
8/46 (15/85)
|
32/32 (50/50)
|
Chi-square
|
P=<0.001*
|
Progress/No progress GPA (%)
|
7/47 (13/87)
|
37/27 (58/42)
|
Chi-square
|
P=<0.001*
|
Average IOP (mmHg) (SD)
at the end of the study
|
15.93 (2.56)
|
16.34 (2.68)
|
T-test
|
P=0.40
|
Average number of medications (SD)
|
1.75 (0.84)
|
2.80 (0.80)
|
T-test
|
P=<0.001*
|
Number of SLT/ No SLT
(%)
|
2/52 (4/96)
|
10/54 (19/81)
|
Chi-square
|
P=0.002*
|
Number of Cataract operation/ No cataract operation (%)
|
4/50 (7/93)
|
11/53 (17/83)
|
Chi-square
|
P=0.02*
|
POAG: primary open-angle glaucoma, EXFG: exfoliation glaucoma, MD: mean deviation, SD: standard deviation, VFI: visual field index, GPA: guided progression analysis, IOP: intraocular pressure, SLT: selective laser trabeculoplasty.
(*) = Significant values.