Table 3 Mean differences in the main outcomes and adverse events in non-randomized studies of interventions after corneal collagen cross-linking (epi-on vs. epi-off)

Kmax (D)

 Vinciguerra et al. 2019^a [47]

− 0.1 ± 4.6

–

20

− 0.4 ± 4.4

–

20

 Jouve et al. 2017^b [52]

− 1.1 ± 4.2

–

40

0.2 ± 5.2

–

40

 Henriquez et al. 2017^a [53]

− 0.9 ± 5.2

–

25

0.1 ± 5.3

–

36

 Eraslan et al. 2017^a [55]

− 1.4 ± 2.6

–

18

− 0.6 ± 3.1

–

18

 Vinciguerra et al. 2016^a [57]

− 1.0 ± 1.5

–

20

− 0.3 ± 1.9

–

20

UDVA (logMAR)

 Rossi et al. 2018 [51]

− 0.1 ± 0.2

–

10

− 0.2 ± 0.2*

–

10*

− 0.1 ± 0.2^Þ

–

10^Þ

 Henriquez et al. 2017 [53]

− 0.1 ± 0.4

–

25

− 0.1 ± 0.2

–

36

 Eraslan et al. 2017 [55]

− 0.0 ± 0.1

–

18

− 0.1 ± 0.2

–

18

CDVA (logMAR)

 Vinciguerra et al. 2019 [47]

− 0.1 ± 0.1

–

20

− 0.1 ± 0.2

–

20

 Rossi et al. 2018 [51]

− 0.1 ± 0.1

–

10

− 0.1 ± 0.0*

–

10*

− 0.1 ± 0.1 ^Þ

–

10^Þ

 Jouve et al. 2017 [52]

− 0.1 ± 0.1

–

40

− 0.1 ± 0.2

–

40

 Henriquez et al. 2017 [53]

− 0.1 ± 0.1

–

25

− 0.1 ± 0.1

–

36

 Eraslan et al. 2017 [55]

− 0.1 ± 0.1

–

18

− 0.1 ± 0.1

–

18

 Vinciguerra et al. 2016 [57]

− 0.0 ± 0.1

–

20

− 0.1 ± 0.1

–

20

Higher Order Aberrations (µm)

 Vinciguerra et al. 2019 [47]

− 0.1 ± 0.3

–

20

− 0.7 ± 0.2

–

20

 Vinciguerra et al. 2016 [57]

− 0.0 ± 0.2

–

20

− 0.3 ± 0.8

–

20

 Comatic Aberrations

 Vinciguerra et al. 2019 [47]

− 0.3 ± 1.0

–

20

1.7 ± 0.3

–

20

 Rossi et al. 2018 [51]

− 0.4 ± 1.2

–

10

− 0.7 ± 1.4*

–

10*

− 0.7 ± 1.3 ^Þ

–

10^Þ

 Eraslan et al. 2017 [55]

− 0.2 ± 0.3

–

18

− 0.1 ± 0.5

–

18

 Vinciguerra et al. 2016 [57]

− 0.2 ± 0.3

–

20

− 1.2 ± 1.6

–

20

Demarcation Line (depth in µm at 1 month)

 Jouve et al. 2017 [52]

291.0 ± 61.0

–

40

216.0 ± 49.0

–

40

 Eraslan et al. 2017 [55]

272.3 ± 28.6

–

18

136.6 ± 17.9

–

18

 Central corneal thickness (µm)

 Rossi et al. 2018 [51]

− 2.9 ± 18.9

–

10

− 1.6 ± 35.5*

–

10*

− 4.7 ± 30.2 ^Þ

–

10^Þ

Corneal Thinnest Point (µm)

 Vinciguerra et al. 2019 [47]

− 57.0 ± 103.0

–

20

5.0 ± 38.0

–

20

 Henriquez et al. 2017 [53]

− 12.5 ± 40.2

–

25

1.5 ± 51.5

–

36

 Eraslan et al. 2017 [55]

− 11.3 ± 14.9

–

18

− 8.8 ± 14.8

–

18

 Vinciguerra et al. 2016 [57]

− 41.1 ± 35.3

–

20

1.0 ± 7.2

–

20

ECD (cells/mm²)

 Rossi et al. 2018 [51]

− 32.7 ± 99.3

–

10

− 46.1 ± 197.9*

–

10*

− 27.0 ± 62.5^Þ

–

10^Þ

KC progression

 Jouve et al. 2017 [52]

–

3 (7.5%)

40

–

8 (20.0%)

40

 Henriquez et al. 2017 [53]

–

3 (12.0%)

25

–

2 (5.6%)

36

Lost ≥ 2 lines CDVA

 Eraslan et al. 2017 [55]

–

0 (0.0%)

18

–

1 (5.6%)

18

Persistent stromal haze

 Henriquez et al. 2017 [53]

–

1 (0.1%)

25

–

0 (0.0%)

36

 Eraslan et al. 2017 [55]

–

5 (27.8%)

18

–

0 (0.0%)

18

 Sterile infiltrates

 Henriquez et al. 2017 [53]

–

1 (0.1%)

25

–

0 (0.0%)

36