Table 10. Summary of pachymetry outcomes (corneal thickness changes) from representative studies across cross-linking protocols in progressive keratoconus.

A-CXL: accelerated corneal cross-linking; CCT: central corneal thickness; CXL: corneal collagen cross-linking; I-CXL: transepithelial corneal collagen crosslinking using iontophoresis (riboflavin delivery via iontophoresis); NR: not reported; NS: not significant (p-value > 0.05); TCT: thinnest corneal thickness

Study	CXL Protocol	Baseline CCT/TCT	Change	Timepoint	Significance
Wittig-Silva et al., 2014 [35]	Dresden	NR	-19.52 ± 5.06 μm	3 years	p < 0.001
Wittig-Silva et al., 2014 [35]	Control	NR	-17.01 ± 3.63 μm	3 years	p < 0.001
Vinciguerra et al., 2016 [60]	Dresden	NR	-41.1 ± 35.3 μm	1 year	p < 0.001
Vinciguerra et al., 2016 [60]	I-CXL	NR	+1.0 ± 7.2 μm	1 year	NS
Kortuem et al., 2017 [81]	Dresden	457.75 μm	Progressive thinning	3 years	p < 0.05
Kandel et al. (Registry), 2024 [24]	Dresden	NR	-3.0 μm	5 years	NS
Kandel et al. (Registry), 2024 [24]	A-CXL	NR	-11.8 μm	5 years	p < 0.001
Ferdi et al. (Registry), 2023 [2]	Dresden	459 μm	-17 μm	1 year	p < 0.001
Ferdi et al. (Registry), 2023 [2]	Dresden	459 μm	-11 μm	5 years	p < 0.05