Dry eye in allergic conjunctivitis: role of inflammatory infiltrate

Dry-eye associated symptoms are frequently present in patients affected with allergic conjunctivitis. We evaluated the relationship between ocular inflammation and the tear film parameters in patients affected with chronic allergic conjunctivitis. Eighty-two subjects (age 23.00 ± 7.61: range 10-40) affected with chronic allergic conjunctivitis and thirty age- and sex matched healthy controls were enrolled. In all patients tear film qualitative and quantitative tests were performed. To determine the immune activation state, conjunctival biopsies were obtained from the inferior conjunctival fornix. Immunocytochemical markers for CD45RO, CD8, CD20 and EG2 (monoclonal antibody binding eosinophil cationic protein) were evaluated semiquantitatively. All tear film tests were found altered. They were reduced in allergic patients (p<0.001). In conjunctival biopsies of allergic patients a very high number of CD45RO+ and EG2+ cells were found (p<0.001): a lower number of CD45RO+ cells and no EG2+ cells in control biopsies were found. Multivariate analysis showed a significant relationship between tear tests and conjunctival infiltrate (CD45RO+ and EG2+): The tear film alterations are strictly related to the conjunctival immune infiltration. In particular, the reduction of the mucin-related component of tear film can be related to the toxic effect of the granule cationic proteins released by the conjunctival activated eosinophils (EG2+ cells).