Conjunctivitis of allergic origin: clinical presentation and differential diagnosis.

Conjunctivitis of allergic origin is associated with a diversity of clinical presentations. Common features include pronounced itching, a milky conjunctival appearance, a stringy or ropy discharge and papillary hypertrophy of the tarsal conjunctiva in severe cases, and a family history of allergy. The diagnosis should be based on thorough history-taking and careful ophthalmic examination, and, when necessary, confirmation by laboratory testing. An IgE-mediated immediate hypersensitivity mechanism is associated with most types of allergic conjunctivitis, although contact allergy is mediated by lymphocytes rather than antibody. Treatment is based on the diagnosis and severity of signs and symptoms. An array of medications is available to control symptoms, and the regimen of choice should be based on the response to milder forms of therapy and consideration of drug side effects.