Effect of antihistamine eye drops on the conjunctival provocation test with Japanese cedar pollen allergen.

BACKGROUND Approximately 16.2% of the Japanese population suffer from cedar pollinosis, with various manifestations such as ophthalmic, laryngo-pharyngeal and skin symptoms in addition to nasal symptoms. Thus, the annual pollen season is an agonizing period for patients. No study has reported symptoms and their clinical courses after conjunctival provocation with purified cedar pollen allergen Cry j1 as well as suppression of these allergen-induced ocular symptoms by antihistamine eye drops. METHODS Nine patients with Japanese cedar pollinosis who had no nasal or ocular symptoms were included in the present study, after obtaining informed consent in writing. 1) Purified cedar pollen allergen Cry j1 was instilled in the left eye and phosphate-buffered saline (PBS) in the right eye as a control. 2) Levocabastine hydrochloride ophthalmic suspension and ketotifen fumarate ophthalmic solution were respectively instilled in the left and right eyes, which were then challenged with the allergen. Ocular symptoms after provocation with the allergen were recorded through the clinical course. RESULTS Pollen allergen-induced ocular symptoms were itching and hyperemia of the palpebral conjunctiva, and itching lasted for more than 5 hours. Moreover, preadministration of antihistamine eye drops suppressed the increases in the ocular symptom scores, eliminating itching within 1 hour. Allergen provoked not only ocular symptoms but also nasal symptoms in 77.8% of patients. CONCLUSIONS Preadministration of antihistamine eye drops suppressed the symptoms induced by the allergen, which suggests that this is an effective early therapy for Japanese cedar pollinosis, if it is started before the pollen season. However, self-protection by patients using a mask may not be effective enough to suppress nasal symptoms during the pollen season, requiring them to additionally wear glasses to avoid exposure to the allergen.