Eye symptoms of tearing, redness and itching frequently occur in patients with allergic
rhinitis or hayfever. The purpose of this trial is to study whether placing an allergen (a
substance that causes allergies) directly in your nose can cause you to have eye symptoms as
well as nasal symptoms.
Symptoms of conjunctivitis (tearing, redness and itching) frequently occur in patients with
allergic rhinitis. The pathophysiology underlying these symptoms remains to be elucidated.
The symptoms probably arise via a combination of mechanisms including direct contact of
natural pollen with the conjunctiva and reflex mechanisms originating in the nose.
Pollen exposure can result from direct hand transfer of pollen to the conjunctiva or,
conceivably, from the forceful blowing of air, containing nasal secretions with antigen, up
the nasolacrimal duct. The latter mechanism would be considered extremely unlikely because
of the location of the nasolacrimal duct under the inferior turbinate (the duct's location
is in an area with little pollen exposure) and the considerable force of air needed to cause
reverse flow in the duct. The latter would also be true for topically applied intranasal
drugs reaching the conjunctiva via the nasolacrimal duct, whereas the administration of
medications to the conjunctiva frequently results in these medications reaching the nose via
the nasolacrimal duct.
In support of direct contact of pollen as a source of ocular symptoms in patients with
allergic rhinitis is the observation that pollen can be washed out of the conjunctiva on
windy days, although the amount is 10 fold less than the amount of pollen recovered
simultaneously from the nose. Additionally, beginning with Noon in the early 1900s, and
subsequently shown by others, direct conjunctival challenges induce ocular symptoms. Thus,
direct contact is a plausible explanation, but its relative contribution to eye symptoms in
allergic rhinitis is unknown. Since topical intranasal steroids are known to reduce eye
symptoms and the chance of them reaching the eye by systemic absorption or directly when
administered intranasally are very slim, the investigators would postulate that direct
allergen contact at the conjunctiva is a small contributor to the overall ocular symptom
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
Purpose: The investigators will study whether antigen-induced nasal reflexes cause eye
symptoms. The investigators suspect that reflexes occur between the nose and the eye, and
contribute substantially to eye symptoms in allergic patients during the allergy season. The
investigators propose to demonstrate that nasal challenge with antigen leads to increased
- History of grass and/or ragweed allergic rhinitis.
- Positive skin test to grass and/or ragweed antigen.
- Positive response to screening nasal challenge.
- Physical signs or symptoms suggestive of renal, hepatic or cardiovascular disease.
- Pregnant or lactating women.
- Upper respiratory infection within 14 days of study start.