Purpose: With use of the Wong-Kilbourne derivative Chang conjunctival cell line, this study compared in vitro the ocular toxicity of three topical intraocular pressure (IOP)-lowering agents: travoprost 0.004% containing 0.015% benzalkonium chloride (BAK), travoprost Z 0.004%, a new formulation without BAK, and latanoprost 0.005% containing 0.02% BAK.
Methods: Neutral red, Alamar blue, YOPRO-1, and annexin V/7-AAD assays were used to evaluate the effects of the IOP-lowering agents and BAK on cellular viability, membrane integrity, and apoptosis in the conjunctival cell line using microtitration fluorometric analysis and flow cytometry. All assessments were performed in a masked manner.
Results: Assessment of cell viability and membrane integrity revealed a significant effect by latanoprost with BAK or BAK alone but no effect by travoprost Z without BAK or buffer alone (P < 0.0001). Latanoprost with BAK, travoprost with BAK, and BAK alone were cytotoxic in Chang conjunctival cells, whereas no cytotoxicity was observed in cells exposed to travoprost Z without BAK or in cells treated with buffer (P < 0.0001). No increase in apoptosis or necrosis was observed in cells treated with control or travoprost Z without BAK compared with BAK, travoprost with BAK, and latanoprost with BAK (P < 0.0001).
Conclusions: Latanoprost with BAK, travoprost with BAK, and BAK alone have significant cytotoxic effects on human conjunctiva-derived cells and are associated with apoptosis. These effects likely result from BAK used as a preservative. IOP-lowering agents with alternative preservatives instead of BAK will most likely have fewer ocular surface adverse effects than agents containing BAK.