Corneal Cross-Linking and Safety Issues

Eberhard Spoerl*, Anne Hoyer, Lutz E Pillunat , Frederik Raiskup
Department of Ophthalmology, Carl Gustav Carus University Hospital, Dresden, Germany

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© Spoerl et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Department of Ophthalmology, Carl Gustav Carus University Hospital, Fetscherstr. 74, D-01307 Dresden, Germany; Tel: +49 351 458 3763; Fax: +49 351 458 4335; E-mail:



To compile the safety aspects of the corneal collagen cross-linking (CXL) by means of the riboflavin/UVA (370 nm) approach.

Materials and Methodology:

Analysis of the current treatment protocol with respect to safety during CXL.


The currently used UVA dose density of 5.4 J/cm2 and the corresponding irradiance of 3 mW/cm2 are below the known damage thresholds of UVA for the corneal endothelium, lens, and retina. Regarding the photochemical damages due to the free radicals the damage threshold for endothelial cells is 0.35 mW/cm2. In a 400μm thick corneal stroma saturated with riboflavin, the irradiance at the endothelial level is about 0.18 mW/cm2, which is a factor of 2 smaller than the damage threshold.


As long as the corneal stroma treated has a minimal thickness of 400 microns (as recommended), neither corneal endothelium nor deeper structures such as lens and retina will suffer any damages. The light source should provide a homogenous irradiance avoiding hot spots.

Keywords: Keratoconus, biomechanics, cornea, ultraviolet light, cross-linking.