['This study evaluated the cytotoxicity of five prostaglandin analog ophthalmic solutions on four ocular surface cell lines, ie, Chang (human conjunctiva), SIRC (rabbit cornea), RC-1 (rabbit cornea), and BCE C/D-1b (bovine cornea).', 'Cell viability was measured by neutral red and MTT assays in cells treated for 10, 30, or 60 minutes with various doses of prostaglandins (undiluted, and 2- and 10-fold dilutions). The number of cell lines with viability >/=50% in the presence of selected dilution of the drug (CVS(50)) was used for comparison. In addition, 24 cell viability comparisons (four cell lines, two assays, and three exposure times) were made between latanoprost (Xalatan((R))) and each other solution at each dose. A comparison between the newly introduced tafluprost (Tapros((R))) with 0.01% benzalkonium chloride was also made.', 'The order of cell viability determined by CVS(50) was Travatan Z((R)) (travoprost with the SofZia system) > Tapros >/= Travatan((R)) (travoprost) = Xalatan > Rescula((R)) (unoproston). This was consistent with the results of direct comparisons between Xalatan and the other drugs. There was no clear difference in cell viability between Tapros and benzalkonium chloride.'] Does cytotoxicity of prostaglandin analog eye drop preserved with benzalkonium chloride in multiple corneoconjunctival cell lines?