Precision of conjunctival provocation tests in right and left eyes

Conjunctival provocation tests (CPTs) are used for assessing the efficacy of antiallergic treatments, but their reproducibility is not well characterized. A study was carried out to assess the reproducibility of CPTs and the release of mediators during CPTs.

Both eyes of 30 grass-pollen-allergic patients were challenged with threefold increasing concentrations of a standardized orchard grass pollen extract. The positivity of the CPT was assessed by a cumulative symptom score. The release of mediators was examined by means of histamine (radioimmunoassay), prostaglandin D2 and leukotrienes C4 and D4 (enzyme immunoassay).

There was a significant correlation between the concentrations of allergen inducing a positive CPT in both eyes (p < 0.0001, Spearman). All but one patient had a significant release of at least one mediator. After allergen CPT there was a significant release in both eyes in 13 of 20 patients for prostaglandin D2, 11 of 19 for leukotrienes C4 and D4 and 15 of 18 for histamine. The correlations between the levels of mediators released during diluent and allergen challenges in both eyes were significant for prostaglandin D2 (diluent and allergen challenges) and leukotrienes C4 and D4 (allergen challenge).

Considering the whole group of patients, CPT is reproducible in both eyes, but the results are less satisfactory when patients are examined individually.