Purpose: The purpose of this study was to evaluate in a large series the incidence of latent infection during chronic allergic conjunctivitis.
Methods: In a 5-year follow-up prospective, nonrandomized trial, we evaluated 236 patients (472 eyes) with a history of allergic conjunctivitis but without evidence of infection. Conjunctival scrapings were examined cytologically, and antibiograms and antimicrograms were assessed. The 472 eyes were divided into 5 subgroups based on the percent of eosinophilic cells in conjunctival specimens.
Results: Latent concurrent infection was identified in 176 of 472 eyes (37%): Candida albicans (55.2%), Staphylococcus epidermidis (50.9%), Chlamydia trachomatis (30.7%), and Staphylococcus aureus (23%). The incidence of concurrent infection (mainly bacterial infection) strongly correlated with the percent of eosinophilic cells. Concurrent bacterial infection was identified in 26 of 26 cases of the subgroup with the highest percent of eosinophilic cells.
Conclusion: Chronic allergic conjunctivitis may be associated with latent infection. Pathogens can stimulate activation of eosinophils with a consequent worsening and chronicity of allergic symptoms.