The precision of the conjunctival provocation test.

Repeated conjunctival provocation tests (CPT) were done in 20 children with rhino-conjunctivitis due to birch pollen allergy. Compared with the first open challenge, three successive blinded CPTs were reproducible within an allergen strength difference of one 10-potency in 92% of the tests. Based on the data, a power function was constructed, making it possible to determine the number of patients needed to discriminate CPT sensitivity of a given magnitude between two populations. During the study period specific serum-IgE increased in only three of 19 patients, indicating that stimulation of IgE antibody production is not a common consequence of repeated tests. We conclude that CPT is useful in clinical research. When indicated in clinical routine, CPT is a safe and easy test with good precision.