Purpose: Recent histologic studies of conjunctival tissues in patients who have had long-term treatment for glaucoma have shown in situ an abnormal infiltration by inflammatory cells. In this study, conjunctival inflammatory antigens were investigated in impression cytology specimens from patients who have been and those who have not been treated for glaucoma.
Methods: This study included 107 eyes from 55 patients with primary open-angle glaucoma. Of these, 48 had received prolonged topical treatments, all containing benzalkonium chloride as a preservative. Seven glaucomatous eyes could be examined before any treatment. In addition, the authors examined 11 patients (21 eyes) receiving anticataract eye drops preserved with chlorhexidine and 15 normal untreated subjects (30 eyes). In all patients, immunocytochemistry was performed in impression cytology specimens, using two monoclonal antibodies against HLA-DR antigens and receptor to IgE CD23.
Results: None of the untreated eyes showed reactivity for either monoclonal antibody. In contrast, HLA-DR expression by conjunctival cells was found in 43 of 88 treated eyes (mean percentage of reactive cells, 70% +/- 28%) and positive staining for receptor to IgE in 26 of 68 eyes (52% +/- 28% of conjunctival cells). Results were not related to a specific treatment or combination of anti-glaucoma drugs. However, the proportion of positive specimens (3/14 for both antigens) in the group receiving chlorhexidine-containing eye drops was significantly lower than that found in the patients with glaucoma.
Conclusion: This study showed abnormal expression of inflammatory markers without clinical inflammation at the level of conjunctival cells in repetitive contact with various anti-glaucomatous treatments and their common preservative, benzalkonium chloride. Failure in filtering glaucoma surgery was found to be related to prolonged medical treatment; therefore, a topical sensitization to preservatives and/or anti-glaucoma drugs has been hypothesized. An immunocytologic test thus could be useful for qualitative and quantitative investigation of drug-induced conjunctival inflammation and predict high-risk patients.