Table 3 Development of mean defect of standard automated perimetry (SAP) and mean peripapillary retinal nerve fibre layer (RNFL) thickness during 24 months of postoperative follow-up after trabeculectomy (TE) or PRESERFLO (PF) implantation

SAP mean defect (dB)

Baseline

 − 11.54 ± 0.93

(10.50, 9.70)

n.a

 − 11.17 ± 1.66

(10.20, 6.60)

n.a

0.892

6 months

 − 11.60 ± 1.56

(11.50, 9.50)

0.407

 − 11.16 ± 3.82

(10.20, 5.50)

0.180

0.859

12 months

 − 11.57 ± 1.07

(12.60, 9.00)

0.147

 − 13.12 ± 4.20

(11.30, 2.60)

0.868

0.914

24 months

 − 10.67 ± 0.91

(11.30, 10.60)

0.226

 − 10.40 ± 4.75

(10.80, 3.80)

0.628

0.123

RNFL thickness (µm)

Baseline

62.79 ± 1.94

(58.50, 26.00)

n.a

62.62 ± 2.05

(57.00, 22.80)

n.a

0.545

3 months

61.27 ± 3.05

(58.00, 26.00)

0.174

60.99 ± 2.02

(57.00, 24.00)

0.079

0.892

6 months

58.67 ± 2.75

(54.00, 25.00)

 < 0.001

60.36 ± 2.00

(57.00, 23.60)

0.275

0.344

12 months

58.97 ± 2.39

(57.00, 27.50)

 < 0.001

60.04 ± 2.10

(60.00, 23.50)

0.857

0.584

24 months

57.41 ± 1.81

(54.00, 27.00)

 < 0.001

60.22 ± 1.98

(60.00, 22.80)

0.182

0.453