Background: Allergic patients often complain of eye symptoms during the allergy season. A possible mechanism for these eye symptoms is a nasal ocular reflex.
Objective: To demonstrate eye symptoms after nasal allergen challenge.
Methods: In a double-blind, placebo-controlled, crossover, clinical trial, 20 patients with seasonal allergic rhinitis were challenged in 1 nostril with antigen, and the response was monitored in both nostrils and in both eyes. Symptoms were recorded. Filter paper disks (intranasally) and Schirmer strips (intraocularly) were used for collecting secretions, which were subsequently eluted for the measurement of histamine and albumin levels. Patients were treated once topically at the site of challenge with azelastine or placebo.
Results: After placebo treatment, ipsilateral nasal challenge caused nasal symptoms and an increase in secretion weights; both were blocked by treatment with azelastine. Histamine and albumin levels increased only at the site of nasal challenge. Azelastine pretreatment inhibited the increase in albumin but not histamine levels. Symptoms of itchy and watery eyes increased significantly compared with symptoms with sham challenge after nasal allergen and were blocked by azelastine use. Ocular secretion weights increased bilaterally after placebo use and were not inhibited by azelastine use.
Conclusions: Nasal allergen challenge releases histamine at the site of the challenge, which probably initiates a nasonasal and a nasal ocular reflex. This reflex is reduced by an H1-receptor antagonist applied at the site of the challenge. The eye symptoms associated with allergic rhinitis probably arise, in part, from a naso-ocular reflex.
Trial registration: ClinicalTrials.gov NCT00117832.