Influence of Benzalkonium Chloride on Langerhans Cells in Corneal Epithelium and Development of Dry Eye in Healthy Volunteers

Abstract

Purpose: To investigate the influence of benzalkonium chloride (BAC) on corneal Langerhans cells (LCs) and on the development of dry eye.

Methods: A randomized double-blind clinical trial was performed in 20 healthy volunteers. One eye of each subject was treated with a 0.01% BAC solution (and the fellow eye with a placebo solution) three times daily for 12 weeks. The distribution and density of LCs in the central and peripheral corneal epithelium were evaluated by in-vivo confocal laser-scanning microscopy (CLSM). The subjects were monitored for dry eye (subjective discomfort, slit-lamp biomicroscopy, tear film break-up time, Schirmer’s test).

Results: In the BAC group, compared with placebo, a marked increase in LC density was found in the central cornea at Week 6 and in the central and peripheral cornea at Week 12. LC density then decreased again in both zones after the end of treatment, falling toward (or even below) baseline levels. Significant changes in the LC count relative to baseline were found at Week 12 in the central and peripheral cornea in the BAC group as well as in the peripheral cornea in the placebo group. LC density in the BAC group increased more rapidly in the central than in the peripheral cornea. During therapy the BAC group showed no signs of dry eye.

Conclusion: 12-week application of a 0.01% BAC solution in healthy volunteers induces a significant increase in LCs in the central cornea at Week 12 without dry-eye changes. The return of LC counts toward (or even below) baseline levels just four weeks after the end of BAC administration demonstrates the rapid normalization of the inflammatory environment.

KEYWORDS::

• Benzalkonium chloride
• Confocal microscopy
• Cornea
• Dry eye
• Langerhans cells

ACKNOWLEDGMENT

This study was supported in part by Chibret, Haar/Germany, by the DFG (Transregio 37, Micro- und Nanosystems in Medicine—Reconstruction of Biological Functions) and by an internal grant from the University of Rostock (FORUN N 889009). The authors are grateful to Mr. David Beattie for editorial support.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.