This review discusses the evidence concerning the effect of topical medications and their preservatives on the ocular surface in
glaucoma patients. The role of topical anti-
glaucoma medication remains critical in the management of chronic
glaucoma worldwide but the beneficial effects of treatment are counterbalanced by the adverse effects of corneal and conjunctival toxicity. Areas covered: This article covers the effect of topical ocular drops and preservatives, particularly
benzalkonium chloride, on the cornea and conjunctiva. Both basic science and clinical evidence will be presented. The first part reviews the relationship between ocular surface disease and
benzalkonium chloride and the evidence from non-
benzalkonium chloride preserved drops. The second part discusses the effects of
benzalkonium chloride on the histopathology of the conjunctiva and its impact on clinical care as well as quality of life. Expert opinion: Topical anti-
glaucoma medication will continue to be used in the management of this blinding disease for the foreseeable future. Treatment outcomes will benefit from minimized exposure to
benzalkonium chloride. The development of alternative preservatives, preservative-free topical options, and non-drop
therapeutics such as
drug-eluting systems for the delivery of ocular medications, will be very helpful in the care of
glaucoma patients.