title: Online human conjunctival vessel diameter analysis. A clinical-methodical study.
abstract: BACKGROUND
  The present study investigates the possible application of a commercially available on-line measuring device of retinal vessels for conjunctival vessel assessment.
  
  
  METHODS
  Repeated measurements in one randomly chosen eye were performed in 11 healthy volunteers (mean age 42.9 +/- 10 years). Measurements of one conjunctival vessel were obtained first without a stimulus followed by measurements after the application of one drop of a topical vasoconstrictor. The examinations were performed by Retinal Vessel Analyzer (RVA, IMEDOS/Germany). This system determines automatically on-line the vessel diameter along a chosen vessel segment.
  
  
  RESULTS
  Measurements in the native state without eye drop application showed an intraclass correlation coefficient of 0.97 and a mean variation coefficient of 1.8%. After application of the topical vasoconstrictor a short acting vasodilatation was observed with a magnitude of +10.9% +/- 14.9 (p < 0.001), followed by an increasing vasoconstriction (after 4 min -12.0% +/- 7.6; p = 0.004). One volunteer had no measurable conjunctival vessels in the baseline measurements and was therefore excluded from the study.
  
  
  CONCLUSIONS
  The suggested technique allows the measurement of changes in conjunctival vessel diameter with high precision. The method represents a non invasive technique for the assessment of effects on conjunctival vessels caused by topical or systemic drugs.
authors.affiliation: e_a_nagel@t-online.de
authors.forename: Edgar
authors.initials: E
authors.lastname: Nagel
authors.forename: Walthard
authors.initials: W
authors.lastname: Vilser
authors.forename: Ines
authors.initials: I
authors.lastname: Lanzl
mesh_terms: D000328:Adult; D003228:Conjunctiva / Q000098:blood supply*; D006801:Humans; D008833:Microcirculation; D008875:Middle Aged; D009862:Online Systems; D019721:Ophthalmoscopes; D009887:Ophthalmoscopy / Q000379:methods; D012171:Retinal Vessels; D012984:Software; D014661:Vasoconstriction; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology; D014664:Vasodilation
chemical_list: D014662:Vasoconstrictor Agents