Evaluation of Ocular Surface Toxicity in Rabbits Following Exposure to Preservative-Free Tafluprost, Commercially Available Latanoprost and 0.02% Bac

Abstract

Purpose: : The preservative benzalkonium chloride (BAK) has shown dose-dependent toxic effects on ocular surface. BAK-free prostaglandin analogues are in development for glaucoma treatment. This study evaluates the conjunctival and corneal reactions in rabbits of the preservative-free tafluprost, a new prostaglandin analogue.

Methods: : Four groups of 6 male New Zealand albino rabbits received preservative-free tafluprost 0.0015%; a commercially available solution of latanoprost 0.005% containing 0.02% BAK; 0.02% BAK alone or phosphate-buffered saline (PBS) 15 times at 5-min intervals. Ocular surface toxicity was examined using in vivo confocal microscopy, flow cytometry on conjunctival impression cytology and classical cytological and immunohistological methods.

Results: : Clinical observation using slit-lamp revealed the highest toxicity for BAK alone and latanoprost, while preservative-free tafluprost showed similar results to PBS. In vivo confocal microscopy demonstrated severe damages in the epithelium and marked inflammatory infiltration with latanoprost and BAK but normal structures with preservative-free tafluprost and PBS. Flow cytometry showed a higher expression of CD45 and TNFR1 in latanoprost or BAK-instilled groups, compared with preservative-free tafluprost and PBS groups; latanoprost induced fewer positive cells compared with BAK alone. On cryosections, infiltration of CD45+ inflammatory cells and TUNEL+ apoptotic cells was higher in limbal and conjunctival areas of latanoprost and BAK-treated eyes, compared with preservative-free tafluprost and PBS-treated eyes.

Conclusions: : Rabbit corneoconjunctival surface showed better tolerance when treated with preservative-free tafluprost compared with commercially available latanoprost or 0.02% BAK-solution.

Keywords: drug toxicity/drug effects • flow cytometry • microscopy: confocal/tunneling