title: Quantification of conjunctival vascular reaction by digital imaging.
abstract: BACKGROUND
  No objective evaluation of the conjunctival provocation test (CPT) was possible until now.
  
  
  OBJECTIVE
  The aim of this study was to develop a tool that would enable us to monitor conjunctival allergic inflammation by objective measurements.
  
  
  METHODS
  Twenty-four patients allergic to grass pollen were challenged by a CPT with grass pollen and genuine grass pollen in the "Vienna Challenge Chamber." Patients were randomized to treatment with placebo or topical application of an H1-receptor antagonist (azelastine). Vascular reaction of the conjunctiva was repeatedly monitored by special video equipment. The signal was sent to a digital frame grabber, and digital image analysis was done with the aid of the WCUE-3 program (Olympus Optical Co., Hamburg, Germany).
  
  
  RESULTS
  The CPT led to an immediate increase of the red density. This extension was linear within the first 15 minutes. During the long-term challenge, the increasing vascular effect lasted 2 hours. During active treatment a consistent reaction pattern was obvious; however, the corresponding levels were statistically lower (p = 0.022).
  
  
  CONCLUSIONS
  The calculation of red density of the conjunctiva by digital analysis proved to be a sensitive tool for measuring the conjunctival allergic reaction. It is possible to overcome the insufficient subjective evaluation of the CPT by objective measurements of the vascular reaction.
authors.affiliation: University Ear Nose and Throat Clinic, Vienna, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Horak
authors.forename: U
authors.initials: U
authors.lastname: Berger
authors.forename: R
authors.initials: R
authors.lastname: Menapace
authors.forename: N
authors.initials: N
authors.lastname: Schuster
mesh_terms: D000328:Adult; D000485:Allergens / Q000494:pharmacology; D003228:Conjunctiva / Q000098:blood supply*; D003233:Conjunctivitis, Allergic / Q000175:diagnosis* / Q000503:physiopathology*; D003952:Diagnostic Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D010865:Pilot Projects; D006109:Poaceae / Q000276:immunology; D011058:Pollen / Q000276:immunology
chemical_list: D000485:Allergens