The effect of preservatives and antiglaucoma treatments on the ocular surface of mice with dry eye.

PURPOSE: To test the hypothesis that benzalkonium chloride (BAK) alters the ocular surface in normal and dry eye mice and that a BAK-free commercially available antiglaucoma treatment does not induce the same effects.

METHODS

Eight- to 12-week-old female C57BL/6 mice were used under normal environmental conditions and in a controlled environment chamber (CEC) which induces dry eye. Study and control groups included treatment with BAK, bimatoprost, BAK-free travoprost, and 0.9% NaCl and nontreated mice exposed and nonexposed to the CEC, respectively. Treatments were instilled 4 times a day in the right eye for 7 days. Aqueous tear production was measured by cotton thread test, corneal fluorescein staining (score 0-15), corneal thickness, goblet cell density, and CD45(+) cell expression in superior, inferior, and fornix conjunctiva by a masked observer.

RESULTS

After 7 days of treatment with BAK, mice showed significant increase of corneal staining, reduction of goblet cells, and increase of inflammation under normal and CEC conditions. The commercial preparations of bimatoprost containing BAK and travopost did not show the same effects. Travoprost showed a significant corneal thickening under CEC conditions compared to that in all other groups.

CONCLUSIONS

This study indicated that use of BAK has negative effects on the ocular surface under normal and dry eye conditions, even if the association with bimatoprost does not confirm the same results. A BAK-free travoprost preparation showed positive effects on tear secretion and corneal protection.