Comparison of the Conjunctival Effects of Latanoprost versus Preserved and Non-preserved Timolol

Abstract

Abstract: : Purpose: To compare the toxicity of latanoprost on conjunctival epithelium with preserved and unpreserved beta-blockers (BB). A retrospective study using impression cytology (IC) was conducted and completed with an in vitro study on a conjunctival cell line. Methods: 21 eyes treated with latanoprost, 15 eyes with timolol and 0.01% benzalkonium chloride (BAC) (BB,BAC+) and 17 eyes with unpreserved timolol (BB,BAC-) were included and IC performed. Samples were analyzed by flow cytometry for inflammatory profile (using antibodies directed against HLA DR and ICAM-1) and mucin detection (antibody directed against MUC5AC). A continuous human conjunctival cell line was treated with 0.02% BAC timolol, 0.02% BAC and 0.02% BAC containing latanoprost. Membrane integrity was assessed by using a neutral red test and chromatin condensation was evaluated with a Hoechst 33342 test. Results: IC analyses showed a significant increase of the expression of the inflammatory markers in both BB,BAC+ and latanoprost groups but with a significant higher expression in BB,BAC+ group. Significant decrease of goblet cell density was also observed in both BB,BAC+ and latanoprost groups as compared to BB,BAC- group but with a significant higher decrease in BB,BAC+ group. In the in vitro study, after 15 minutes of treatment, an apoptotic phenomenon was observed with timolol and latanoprost significantly less important than the one observed with BAC despite the same concentration. Conclusion: Latanoprost appeared to be less toxic than timolol BAC+, even at the same concentration of preservative, suggesting a cytoprotective effect of prostaglandin upon conjunctival cells.

Keywords: conjunctiva • drug toxicity/drug effects • cornea: surface mucins