Cytotoxicity and antimicrobial activity of six multipurpose soft contact lens disinfecting solutions.
OBJECTIVE
To assess and compare the cytotoxicity and antimicrobial activity of six multipurpose disinfecting contact lens solutions (MPDS).


METHODS
Six MPDS were assessed and compared: MeniCare Soft, Complete Moisture Plus, Solo-Care Aqua, Opti-Free Express, ReNu MultiPlus and ReNuMoistureLoc. Cytotoxicity was evaluated by means of the colony-forming assay (ISO 10993-5) using one cell line. One hundred Chinese hamster's fibroblast V79 cells in 2 mL of medium were inoculated into 6-well plates and cultured for 24 h. After incubation, the medium was removed and 2 mL of each MPDS was diluted with physiological saline and medium and added individually into wells at 1.25, 2.5, 5 and 10% concentrations. After an additional 6 days of incubation, cells were fixed and stained with Giemsa solution. Subsequently, the number of colonies was counted. Cytotoxicity was expressed in terms of the concentration of the MPDS that suppresses colony formation. Antimicrobial activity was evaluated by means of the stand-alone contact lens disinfection test (ISO 14729).


RESULTS
Cytotoxicity--MeniCare Soft and Complete Moisture Plus were not cytotoxic at any of the concentrations tested. The cytotoxicity ranking of the other MPDS was as follows: Solo-Care Aqua approximately equal to Opti-Free Express < ReNu MultiPlus < ReNu MoistureLoc. Antimicrobial activity--All MPDS met the primary criteria of the stand-alone test for bacterial species. ReNu MoistureLoc showed borderline values for Serratia marcescens and Staphylococcus aureus. Complete Moisture Plus failed to meet the stand-alone test criteria for Fusarium solani.


CONCLUSIONS
Large differences in cytotoxicity and antimicrobial activity were found among the MPDS under investigation. Multipurpose disinfecting contact lens solutions with identical concentrations of polyhexamethylene biguanide can behave differently depending on solution formulation. The new MeniCare Soft showed effective antimicrobial activity and minimal cytotoxicity.
Santodomingo-Rubido
Jacinto
J
Menicon Co. Ltd, 21-19, Aoi 3 Naka-Ku, Nagoya 460-0006, Japan. j.santodomingo@menicon.com
Mori
Osamu
O
Kawaminami
Satoshi
S
D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002021:Buffers; D002460:Cell Line; D015169:Colony Count, Microbial / Q000379:methods; D018639:Contact Lens Solutions / Q000494:pharmacology*; D003263:Contact Lenses, Hydrophilic; D006224:Cricetinae; D003412:Cricetulus; D004203:Disinfection / Q000379:methods*; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D007552:Isotonic Solutions / Q000494:pharmacology; D008168:Lung / Q000166:cytology
D000890:Anti-Infective Agents; D002021:Buffers; D018639:Contact Lens Solutions; D007552:Isotonic Solutions