Quantification of conjunctival vascular reaction by digital imaging

J Allergy Clin Immunol. 1996 Sep;98(3):495-500. doi: 10.1016/s0091-6749(96)70081-7.


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).

Conclusion: 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.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Allergens / pharmacology
  • Conjunctiva / blood supply*
  • Conjunctivitis, Allergic / diagnosis*
  • Conjunctivitis, Allergic / physiopathology*
  • Diagnostic Imaging / methods*
  • Humans
  • Image Processing, Computer-Assisted
  • Pilot Projects
  • Poaceae / immunology
  • Pollen / immunology


  • Allergens