Abstract
Abstract: :
Purpose:Bacterial biofilm on contact lenses has been cited as a possible cause of corneal infection and acute red eye. A contact lens coating that blocks biofilm formation might reduce the frequency of these clinically significant problems. Selenium compounds can catalyze the formation of superoxide radicals in the tear film which are cytotoxic to bacteria. Thus, this study investigated the safety and effectiveness of a covalent organo-selenium coating on silicone hydrogel (balafilcon A) contact lenses. Methods:1) The inhibition of biofilm formation with the organo-selenium coating was investigated by incubating coated and uncoated contact lenses in a nutrient broth containing either Pseudomonas aeruginosa or Staphylococcus aureus for four days at 37 degrees C. Lenses were rinsed with saline and fixed with glutaraldehyde. Lenses were imaged with a scanning electron microscope to observe biofilm formation. 2) The safety of the organo-selenium coating was investigated by having New Zealand albino rabbits continuously wear a coated lens in one eye and uncoated lens in the other eye, for two weeks to two months. Epithelial and full thickness corneal pachymetry was measured pre- and post-wear. Slit lamp observations with fluoroscein stain were made on a weekly basis. Corneas were examined histologically at the end of the experiment. 3) Contact lenses were also examined chemically for protein and lipid deposition. Results:1) Electron micrographs showed little or no bacterial biofilm formation on the coated lenses and extensive biofilm formation on the uncoated lenses with both bacteria tested. 2) Pachymetry, histology, and slit lamp evaluation showed no difference between eyes that wore a coated versus an uncoated lens for up to two months. 3) There was no significant difference in protein or lipid deposition between the coated and uncoated lenses. Conclusion:The organo-selenium coating successfully blocked the formation of a bacterial biofilm on the balafilcon A silicone hydrogel material in vitro. In addition, the coated lenses had no deleterious effects on the corneas of New Zealand albino rabbits.
Keywords: 367 contact lens • 369 cornea: clinical science • 494 ocular irritancy/toxicity testing