Cytotoxicity evaluation of three tear substitutes used in the treatment ofdry eye syndromes

Purpose: To investigate cell tolerance of three tear substitutes used in th e treatment of dry eye syndromes. Methods: Cytotoxicity tests were done on a continuous human conjunctival ce ll line using microplate cold light cytofluorimetry. Membrane integrity, DN A condensation and reactive oxygen species (ROS) production (hydrogen perox yde and superoxide anion) were evaluated after 15 minutes of treatment or 1 5 minutes and 24 hours of cell recovery. Hyaluronic acid, hydroxypropyl met hylcellulose associated with sodium perborate (HPMC) and carbomer 934P were tested at their commercial concentrations (respectively 0.18%, 0.3% and 0. 3%) and after a 1/10 dilution. Results: Cell viability and chromatin condensation were not altered by hyal uronic acid for all concentrations and times tested. A decrease in membrane integrity was observed with 0.3% carbomer 934P after 24 hours of cell reco very and with 0.3% HPMC after 15 minutes. This decrease was amplified after 24 hours and associated with an apoptotic phenomenon. A H2O2 production wa s observed with HPMC associated with sodium perborate and an O-2 production was found with hyaluronic acid diluted at 1/10. Conclusion: Hyaluronic acid, carbomer and HPMC are in vitro well-tolerated even if HPMC induces a more important decrease of cell viability compared t o the other drugs. Hyaluronic acid, with its theologic properties, with no in vitro toxicity, seems to be efficient for dry eye patients.