Table 8. Summary of corneal haze rates across corneal collagen cross-linking protocols in progressive keratoconus.

A-CXL: accelerated corneal cross-linking; CXL: corneal collagen cross-linking; I-CXL: transepithelial corneal collagen crosslinking using iontophoresis (riboflavin delivery via iontophoresis); NR: not reported

Study	CXL Protocol	Haze Rate	Severity	Resolution
Kortuem et al., 2017 [81]	Dresden	70.5%	Variable	Progressive improvement
Kortuem et al., 2017 [81]	A-CXL	46.9%	Variable	Progressive improvement
Bhattacharyya et al., 2019 [15]	Dresden	All patients	Transient	Resolved by 3 months
Ferdi et al. (Registry), 2023 [2]	Dresden	15.1% at 1 year	Variable	NR
Ferdi et al. (Registry), 2023 [2]	Dresden	1.9% at 5 years	Variable	NR
Kandel et al. (Registry), 2024 [24]	Dresden	3% at 5 years	Variable	Resolution in 77%
Kandel et al. (Registry), 2024 [24]	A-CXL	2% at 5 years	Variable	Resolution in 88%
Alqudah et al., 2025 [14]	I-CXL	7%	Mild	NR
Alqudah et al., 2025 [14]	Dresden	54% mild	Mild	NR