Riboflavin Concentrations at the Endothelium During Corneal Cross-Linking in Humans.
- 2019-05-18
Published in:
- Investigative ophthalmology & visual science. - 2019
Cadaver
Collagen
Corneal Stroma
Cross-Linking Reagents
Descemet Membrane
Endothelium, Corneal
Humans
Photosensitizing Agents
Riboflavin
Ultraviolet Rays
English
Purpose
To determine the riboflavin concentration in the posterior corneal stroma, Descemet's membrane, and endothelium prior to UV irradiation in corneal cross-linking (CXL) in humans.
Methods
Five human deepithelialized cadaver corneas were mounted into artificial anterior chambers. After the establishment of stable physiological hydration, two-photon imaging with a certified multiphoton tomograph was used to determine fluorescence intensity and second harmonic generation signals from collagen throughout each cornea by optical sectioning, with a step size of 2.5 μm. Afterward, 0.1% riboflavin solution was applied to the anterior corneal surface, similar to the standard CXL protocol. To determine the absolute riboflavin concentration immediately before UV irradiation, corneas were measured by two-photon imaging just at the end of the riboflavin imbibition and after riboflavin saturation.
Results
The topical application of 0.1% riboflavin results in a riboflavin concentration that decreases to 0.035% in the posterior stroma. Inside Descemet's membrane and endothelium, the concentration drops further to only approximately 0.015% at the endothelial level. Local riboflavin distribution indicates a predominantly paracellular passive diffusion of riboflavin into the anterior chamber.
Conclusion
The experimentally determined riboflavin concentration of 0.015% at the endothelium shows a substantial discrepancy of a factor of 1.7 to the previously theoretically calculated 0.025%. A lower riboflavin concentration at the endothelium may enable higher radiant exposures and further improve the efficacy of CXL.
To determine the riboflavin concentration in the posterior corneal stroma, Descemet's membrane, and endothelium prior to UV irradiation in corneal cross-linking (CXL) in humans.
Methods
Five human deepithelialized cadaver corneas were mounted into artificial anterior chambers. After the establishment of stable physiological hydration, two-photon imaging with a certified multiphoton tomograph was used to determine fluorescence intensity and second harmonic generation signals from collagen throughout each cornea by optical sectioning, with a step size of 2.5 μm. Afterward, 0.1% riboflavin solution was applied to the anterior corneal surface, similar to the standard CXL protocol. To determine the absolute riboflavin concentration immediately before UV irradiation, corneas were measured by two-photon imaging just at the end of the riboflavin imbibition and after riboflavin saturation.
Results
The topical application of 0.1% riboflavin results in a riboflavin concentration that decreases to 0.035% in the posterior stroma. Inside Descemet's membrane and endothelium, the concentration drops further to only approximately 0.015% at the endothelial level. Local riboflavin distribution indicates a predominantly paracellular passive diffusion of riboflavin into the anterior chamber.
Conclusion
The experimentally determined riboflavin concentration of 0.015% at the endothelium shows a substantial discrepancy of a factor of 1.7 to the previously theoretically calculated 0.025%. A lower riboflavin concentration at the endothelium may enable higher radiant exposures and further improve the efficacy of CXL.
- Language
-
- English
- Open access status
- gold
- Identifiers
-
- DOI 10.1167/iovs.19-26686
- PMID 31099830
- Persistent URL
- https://sonar.ch/global/documents/113
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