Table 11. Summary of corneal stromal demarcation line depth outcomes from representative studies across cross-linking protocols in progressive keratoconus.

A-CXL: accelerated corneal cross-linking; AS-OCT: anterior segment optical coherence tomography; cl-ACXL: continuous light-accelerated corneal cross-linking; CXL: corneal collagen cross-linking; EFPL-M-TECXL: transepithelial enhanced fluence pulsed light accelerated CXL; eRF: enhanced riboflavin; I-CXL: transepithelial corneal collagen crosslinking using iontophoresis (riboflavin delivery via iontophoresis); μm: micrometer; NR: not reported; NS: not significant (p-value > 0.05); pl-ACXL: pulsed light-accelerated corneal cross-linking; RF: riboflavin; WMD: weighted mean difference

Study	CXL Protocol	Demarcation Line Depth (via AS-OCT)	Comparison
Bikbova et al., 2016 [39]	I-CXL	172 ± 16 μm	vs Dresden: 292 μm  (p < 0.001)
Dervenis et al., 2020 [17]	Dresden	322.50 μm	vs pl-ACXL: 319.95 μm (NS)
Kobashi et al., 2020 [12]	Dresden	Deeper than A-CXL (actual values NR)	WMD vs A-CXL: -102.25 μm 95% CI: -157.16 to -47.35 (p < 0.001)
Mazzotta et al., 2022 [52]	TE-EFPL ACXL	282.6 ± 23.6 μm	NR
Karotkar et al., 2022 [80]	pl-ACXL	251.13 ± 18.28 μm	vs cl-ACXL: 245.28 μm  (NS)
Manumuraleekrishna et al., 2024 [83]	A-CXL (Iso-osmolar RF)	252 μm	vs hypo-osmolar: 210 μm (NS)
Dina et al., 2025 [69]	A-CXL	278.9 ± 31.71 μm	vs Dresden: 280.42 μm  (NS)