Assessment of the Time Course of Itching, Redness, Eyelid Swelling, and Chemosis as Induced by the Conjunctival Allergen Challenge Model of Acute Allergic Conjunctivitis

Abstract

Abstract: : Purpose:To evaluate the onset and duration of the signs and symptoms of allergic conjunctivitis; itching, redness, lid swelling, and chemosis as induced by the conjunctival allergen challenge (CAC) model. Methods:This was a prospective, allergen challenge study. At Visit 1, a CAC was performed bilaterally with antigen until a positive allergic response (≷2.0 ocular redness in one of three vessel beds and ≷2.0 ocular itching, on a scale 0-4, in both eyes within 10 minutes of receiving the dose of antigen) was achieved. At Visit 2 (N=111), one drop of the antigen dose that elicited a positive reaction at Visit 1 was administered bilaterally. Following the antigen challenge, itching was graded by the subjects every 30 seconds for 20 minutes; redness in each of the three vessel beds was graded by the investigator every 5 minutes for 40 minutes. Lid swelling (graded by the subject) and chemosis (graded by the investigator) were evaluated every 5 minutes from 20 minutes to 40 minutes post challenge. Clinically significant changes were defined as 1 unit or greater changes from baseline. Results:Itching was clinically significant within one minute following the antigen challenge, peaked between 3 and 12 minutes, with absolute peak at 7 minutes, and degraded thereafter. There were no significant differences between redness scores in any of the three vessel beds. Clinically significant redness occurred 5 minutes post-challenge, and persisted throughout the entire 40-minute observation period. Chemosis peaked at 25 minutes post-challenge, but did not reach the level of clinical significance. Lid swelling was clinically significant at its peak 20-25 minutes post-challenge, and decreased thereafter. Conclusion:This study demonstrated the time course of the signs and symptoms of allergic conjunctivitis following an antigen challenge. The study population was selected based on their response with itching and redness after the initial antigen challenge. Inclusion of subjects based on chemosis and lid swelling, by challenging subjects at a higher level of antigen or selecting those who respond with higher chemosis and lid swelling scores, would help to evaluate the time course of these symptoms at a clinically significant level.

Keywords: 366 conjunctivitis • 437 inflammation • 359 clinical research methodology