title: Permeability of the blood-retinal barrier in healthy humans. European Concerted Action on Ocular Fluorometry.
abstract: BACKGROUND
  The aim of this study was to compare the inward permeability of the blood-retinal barrier in healthy subjects from six European cities.
  
  
  METHODS
  Seventy-two healthy subjects (age 20-70 years) were selected. At 30 min and 60 min after fluorescein injection, fluorescein mass in vitreous was calculated from the concentrations measured along the optical axis of the eye. Non-protein-bound fluorescein (NPBF) concentrations were measured in plasma prepared from blood samples taken 7, 15 and 55 min after injection. Blood-retinal barrier permeability (PBRB) was calculated from the vitreous fluorescein mass and the time integral of NPBF and was corrected for the autofluorescence of ocular tissue and for lenticular light transmittance.
  
  
  RESULTS
  Mean PBRB values +/- SD (nm.s-1) were 2.07 +/- 0.54 (Coimbra), 2.01 +/- 0.43 (Frankfurt), 2.24 +/- 0.50 (Ghent), 2.37 +/- 0.56 (Herlev), 1.89 +/- 0.44 (Leiden) and 1.74 +/- 0.38 (Porto). Differences between centers were not significant (P > 0.35). Measurements were reproducible and independent of the time after fluorescein injection (P > 0.50). A PBRB higher than 3.16 nm.s-1 or a value which had increased by 32% was considered abnormal (P < 0.05).
  
  
  CONCLUSIONS
  PBRB values were similar in all centers. The results demonstrate that this is a highly sensitive and reliable method for measuring the permeability of the blood-retinal barrier.
authors.affiliation: Department of Ophthalmology, Leiden University Medical Center, The Netherlands.
authors.forename: H J
authors.initials: HJ
authors.lastname: Van Schaik
authors.forename: B
authors.initials: B
authors.lastname: Heintz
authors.forename: M
authors.initials: M
authors.lastname: Larsen
authors.forename: E
authors.initials: E
authors.lastname: Leite
authors.forename: V
authors.initials: V
authors.lastname: Rosas
authors.forename: R
authors.initials: R
authors.lastname: Schalnus
authors.forename: J A
authors.initials: JA
authors.lastname: Van Best
mesh_terms: D000328:Adult; D000368:Aged; D001813:Blood-Retinal Barrier / Q000502:physiology*; D002199:Capillary Permeability / Q000502:physiology*; D003287:Contrast Media / Q000493:pharmacokinetics; D005060:Europe; D005260:Female; D019793:Fluorescein / Q000493:pharmacokinetics; D015590:Fluorophotometry / Q000379:methods*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019793:Fluorescein