Tear Eosinophil Cationic Protein Levels in Allergic Keratoconjunctivitis

ABSTRACT

PURPOSE: To evaluate tear eosinophil cationic protein (ECP) as a severity marker for atopic keratoconjunctivitis (AKC) and seasonal/perennial allergic conjunctivitis (SAC/PAC). METHODS: Tear ECP levels were measured by chemiluminescent immunometric assay in 7 eyes of 7 patients with AKC, 13 eyes of 13 patients with SAC/PAC, and 10 eyes of 10 healthy control subjects. All AKC and SAC/PAC patients underwent conjunctival injection and papillary formation grading. Tear ECP levels were investigated with reference to the clinical parameters of allergic conjunctivitis (papillary formation and conjunctival injection scoring). RESULTS: Tear ECP levels in patients with AKC were significantly higher than those in patients with SAC/PAC and in control subjects (p = 0.012 and p = 0.003, respectively). The number of patients with papillary formation scores of 2-3 was significantly higher in the AKC group than in the SAC/PAC group (p = 0.016). The number of patients with conjunctival injection scores of 2-3 did not significantly differ between the AKC and SAC/PAC groups (p = 0.128). All AKC patients obtained papillary formation scores of 2-3, and tear ECP levels in patients with conjunctival injection scores of 2-3 were significantly higher than in patients with scores of 0-1 in the AKC group (p < 0.001). In the SAC/PAC group, tear ECP levels in patients with papillary formation scores of 2-3 were significantly higher than in patients with scores of 0-1 (p = 0.046). CONCLUSIONS: This study suggests that tear ECP was a useful marker to diagnose and assess the severity of disease in patients with AKC as well as SAC/PAC. It would be useful to monitor therapeutic outcome in allergic conjunctivitis.