Allergic conjunctivitis occurs when the clear layer of tissue
lining the eyelids and covering the white of the eye
(conjunctiva) become swollen or inflamed due to a reaction to
pollen, dander, mold, or other allergy-causing substances.
Conjunctivitis - allergic seasonal/perennial; Atopic
keratoconjunctivitis Causes, incidence, and risk factors When
your eyes are exposed to anything to which you are allergic,
histamine is released and the blood vessels in the conjunctiva
become swollen. Reddening of the eyes develops quickly, along
with itching and tearing. The pollens that cause symptoms vary
from person to person and from area to area. Tiny, hard-to-see
pollens that may cause hay fever include: The amount of pollen
in the air can affect whether you develop symptoms. There is
more likely to be increased amounts of pollen in the air on hot,
dry, windy days. On cool, damp, rainy days most pollen is washed
to the ground. Allergies tend to run in families, although they
are not inherited in any obvious way. It is