[Childhood allergic conjunctivitis: the allergist's point of view].

Allergic conjunctivitis is one of the most frequent reasons for a child's consultation with an ophthalmologist. Once the diagnosis of conjunctivitis is made and the clinical form is clearly established, the search for a cause is the most complicated step. Consultation with an allergist is necessary, in particular when questioning the patient points toward an allergic cause or brings up conditions suggestive of atopic disease. Ocular allergy can follow a type I hypersensitivity, i.e., mediated by IgE: most frequently this is acute and chronic allergic conjunctivitis. Demonstrating the allergen requires prick tests, which are easy to carry out and painless; their sensitivity is currently satisfactory. In vitro tests can complete the workup. In case of doubt on the allergen responsability for allergy, an allergenic provocation test can confirm or refute the allergen's involvement. Ocular allergy can also stem from a type IV mechanism, i.e., a cell-mediated mechanism such as in contact allergy involving different topical substances. In these cases, the clinical aspect and the patient's history may require consultation with a dermatologist-allergist for patch tests. To adapt practices when encountering conjunctivitis in a child, the ophthalmologist should be familiar with the allergens that may set off a conjunctivitis episode. Knowledge of the mechanisms at play also helps direct the examination toward allergy or another cause. In all these steps, collaboration between the ophthalmologist and the allergist is indispensable.