[Structural and immunohistochemical changes of conjunctiva induced by topical glaucoma medication]

Abstract

Purpose: The topical medication represents the first line therapy for the primary open angle glaucoma. The study is aimed at assessing the structural and immunohistochemical changes of conjunctiva induced by topical glaucoma medication.

Methods: For this purpose, we carried out a 40 weeks, prospective, experimental, epidemiological-operational and randomized study enrolling 18 patients (36 eyes) with recently primary open angle glaucoma. The eyes were divided into treatment (non-selective beta blockers or selective, prostaglandin analogues, topical carbonic anhydrase inhibitors) in four groups. The assessment was performed by comparison with control group (4 patients) who was instilled with natural tears (with different preservative). Both the cytology and the conjunctival biopsy specimens were investigated by histological exams and immunohistochemistry using different monoclonal antibodies. The study was performed by collaboration with The National Institute of Research and Development in Pathology and Biomedical Sciences-"V. Babes"-Bucharest.

Results: The morphometric analysis of histological sections of conjunctiva showed the following changes: squamous metaplasia (significant increases in the thickness and number of epithelial cell layers), inflammation (increase the number of lymphocytes, macrophages and fibroblasts) and subconjunctival fibrosis. According to the type of medication, we observed the significant increase of subepithelial collagen density and degenerative changes of fibrocytes, the reduction of extracellular matrix and also the up-regulation of antibodies against matrix metalloproteinase and allergic changes. According to structural changes, the immunohistochemistry confirmed the tendency of chronic inflammation.

Conclusions: This study revealed important structural and immunohistochemical changes of conjunctiva after topical glaucoma medication. The category and the intensity of these changes are dependent on the sort of therapy and the topical treatment period. The findings showed that benzalkonium chloride (the most common preservative of antiglaucoma drugs) is a major factor for conjunctival metaplasia.