 Reflex mechanisms within the nose have been shown to occur universally in response to nasal challenge with antigen. Nasal challenge with antigen induces a reflex in the contralateral nasal cavity, known as the nasonasal reflex. This reflex can also be initiated by nasal challenge with cold, dry air and histamine. The contralateral response to antigen, cold dry air and histamine is blocked by topical anticholinergic agents applied to the contralateral side, suggesting that the efferent limb is parasympathetically mediated. Histamine is only released on the side of challenge with antigen but oral H1 antihistamines reduce the contralateral response to unilateral nasal allergen challenge, suggesting that histamine contributes to the initiation of the reflex. The eye is richly innervated by parasympathetic nerves which enter the eye after running in conjunction with the parasympathetic input to the nasal cavity. The investigators, therefore, hypothesize that the conjunctiva will respond to nasal allergen in a manner similar to the contralateral nasal cavity. 