Abstract
Purpose: :
To evaluate the antimicrobial activities of silver salt-infused silicone hydrogel lenses in preventing or retarding in-vitro colonization of the lenses by bacteria and fusaria.
Methods: :
Unworn and worn silicone hydrogel galyfilcon A lenses and galyfilcon A lenses infused with silver iodide were challenged in wells of tissue culture plates in phosphate buffered saline or dilute tryptic soy broth with 104 cells of Pseudomonas aeruginosa and other species associated with adverse ocular events. Cell populations of bacteria were recovered after 20 h and enumerated by standard dilution and plate count procedures. For Fusarium,unworn lenses were studied with and without 2-h exposures in Sabouraud’s dextrose prior to inoculation. Worn lenses were exposed only to phosphate buffer. All lenses were inoculated with 104conidia and examined daily with light microscopy.
Results: :
Near 2-log fewer bacteria were associated in all instances with the silver iodide-infused lenses compared to control lenses (p < 0.05). For non-worn controls, germination of the conidia of Fusarium was delayed for at least 48 hours in the presence of the silver iodide-infused lenses. For worn lenses, none of the lens matrices of galyfilcon A lenses infused with silver iodide were invaded by hyphae after 14 days of incubation whereas greater than 40% of the control lenses were observed having been penetrated by Fusarium starting at day 4.
Conclusions: :
Galyficon A silicone hydrogel lenses with infused silver iodide delay or inhibit colonization by bacteria and fungi associated with adverse ocular events compared to lenses without silver iodide. Silver-iodide infusion of lenses may reduce the risk of the lens serving as a fomite in the transfer of microorganisms from the contact lens case to the eye.
Keywords: contact lens • bacterial disease • fungal disease