Management of glaucoma involves long-term pharmacotherapy with topical antiglaucoma drugs. Most of the antiglaucoma eye drops contain benzalkonium chloride (BAK) as a preservative and BAK is known to often induce ocular surface disturbance. In Japanese glaucoma patients, the prevalence rate of keratopeitheliopathy due to commercially available latanoprost ophthalmic solution is reported to be approximately 35%, which may be related to relatively high concentration of BAK in it (Inoue et al. J Glaucoma 2003; 12: 480). Baudouin et al. (1090) studied the effects of BAK in prostaglandin analogue ophthalmic solutions using several experimental methods assessing cell viability and apoptosis in vitro. On cultured human conjunctival epithelial-like cells, latanoprost with BAK, travoprost with BAK, and BAK alone showed significant cytotoxic effects, whereas no significant cytotoxicic effects was observed in cells exposed to BAK-free travosrost (travoprost Z). Observed effects are most likely to be related with BAK. The data reported are solid, reliable, and impressive. However, it must be noted that a preservative is necessary evil for ophthalmic solutions to avoid contamination by potentially pathogenic micro-organisms. Travoprost Z contains sofZia consisting of zinc, borate, propylene glycol and sorbitol as preservative system instead of BAK.
Preservative is a necessary evil for ophthalmic solutions to avoid contamination by potentially pathogenic micro-organismsThus, further investigations are needed to elucidate potential advantages and disadvantages of this new preservative system, especially in clinical setting. In addition, eye drop-induced adverse effects are more likely to be observed in the corneal epithelium rather than in conjunctival epithelium. It has been suggested that chronic use of preservative-containing eye drops may be associated with the failure of filtering surgery (Broadway et al. Arch Ophthalmol 1994; 112: 1446). Effects of travoprost Z, and other BAK-containing prostaglandin analogue-ophthalmic solutions on the human corneal epithelial cells and tenon fibroblasts deserve future studies.