title: Impact of fluorescein on the antimicrobial efficacy of photoactivated riboflavin in corneal collagen cross-linking.
abstract: OBJECTIVE
  To investigate the effect of fluorescein on the antimicrobial efficacy of photoactivated riboflavin in corneal collagen cross-linking (CXL) in vitro.
  
  
  METHODS
  The ultraviolet light-A (UVA) absorption by fluorescein and riboflavin in different concentrations was analyzed with a spectrophotometer. The killing rate of Staphylococcus aureus strains after CXL with UV-A irradiation using different solutions containing riboflavin and/or fluorescein, was evaluated in vitro.
  
  
  RESULTS
  Fluorescein absorbed UV-A to a significant extent, which augmented with increasing concentration. Moreover, addition of fluorescein to the riboflavin solution contributed to a significant reduction of the killing rate of S. aureus strains after 30 minutes of UV-A irradiation in vitro with a killing rate of 85%, whereas it was 47% in the presence of 2% fluorescein (P = .0247).
  
  
  CONCLUSIONS
  The results indicate that fluorescein competes with riboflavin for the absorption of UV-A during CXL and reduces the antimicrobial effect of the procedure. The authors recommend that physicians treating infectious ulcerative keratitis by CXL should not stain the cornea with fluorescein for visualization of the corneal ulceration prior to CXL
authors.forename: Olivier
authors.initials: O
authors.lastname: Richoz
authors.forename: Zisis
authors.initials: Z
authors.lastname: Gatzioufas
authors.forename: Patrice
authors.initials: P
authors.lastname: Francois
authors.forename: Jacques
authors.initials: J
authors.lastname: Schrenzel
authors.forename: Farhad
authors.initials: F
authors.lastname: Hafezi
mesh_terms: D003094:Collagen / Q000378:metabolism; D015169:Colony Count, Microbial; D003319:Corneal Stroma / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D004347:Drug Interactions; D019793:Fluorescein / Q000737:chemistry / Q000494:pharmacology*; D005456:Fluorescent Dyes / Q000737:chemistry / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D012256:Riboflavin / Q000737:chemistry / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*; D014466:Ultraviolet Rays
chemical_list: D003432:Cross-Linking Reagents; D005456:Fluorescent Dyes; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin; D019793:Fluorescein