Quantification of conjunctival vascular reaction by digital imaging.
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.
Horak
F
F
University Ear Nose and Throat Clinic, Vienna, Austria.
Berger
U
U
Menapace
R
R
Schuster
N
N
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
D000485:Allergens