Elucidating the mechanism underlying the ocular symptoms associated with allergic rhinitis

Ocular symptoms occur in approximately 40% of patients with allergic rhinitis. The purpose of this study was to determine whether nasal challenge with antigen induces a nasal-ocular reflex. We performed a double-blind crossover trial in 20 subjects. A nasal challenge with antigen was performed in one nostril, and the response was assessed in both nostrils and both eyes. Subjects were treated before challenge with either placebo or azelastine, an H(1)-antihistamine. Nasal challenge with antigen led to a nasonasal reflex and a nasal-ocular reflex as manifested by an increase in symptoms and secretion weights. Treatment with azelastine reduced both reflexes. A nasal-ocular reflex follows nasal challenge with antigen and probably contributes to the ocular symptoms associated with allergic rhinitis.