Abstract
Purpose: :
Incidence of contact lens related corneal infection or inflammation has not reduced with the use of silicone hydrogel lenses. These adverse events can be associated with bacterial adhesion to lenses. This study was designed to determine whether lens wear modulates bacterial adhesion to silicone hydrogel lenses.
Methods: :
Ten different silicone hydrogel lens types were used in the study. Nine unworn lenses and fifteen daily-worn lenses for each lens type were used for bacterial adhesion. Three strains of Staphylococcus aureus and Pseudomonas aeruginosa were grown overnight in minimum media containing 3H-uridine and then resuspended in PBS to 1x107 CFU/mL. After washing in PBS, lenses were incubated in bacterial suspensions for 18h. Following washing, the number of total (radioactive) and viable (CFU) bacteria adhered on lens surfaces were estimated.
Results: :
In unworn lenses, the highest adhesion of S. aureus was tolotrafilcon A lenses (4.4x105 CFU/lens), and the lowest to asmofilcon A lenses (2.8x104, p<0.05). Lens wear increased total adhesion of S. aureus to all the lens types tested, with filcon II 3, narafilcon A and enfilcon A lenses showing significantly higher adhesion compared to unworn lenses (p<0.05). Worn asmofilcon A showed the least adhesion with S. aureus. There was no change in viable adhesion of S. aureus to different worn versus unworn lenses. Highest adhesion of P. aeruginosa was to comfilcon A lenses (3.2x106 CFU/lens), and the lowest was to asmofilcon A or balafilcon A lenses (8.9x105, p<0.05). Lens wear significantly increased the total and viable adhesion of P. aeruginosa strains to narafilcon A lenses (p<0.001), and significantly decreased the total and viable adhesion to comfilcon A lenses (p<0.05). P. aeruginosa strains adhered least to worn asmofilcon A lenses.
Conclusions: :
The differences in profiles of bacterial adhesion between worn and unworn silicone hydrogel lenses may be due to the diversity in the lens materials, including the silicone component, water content, surface treatment, hydrophobicity, and oxygen transmissibility, and the interaction of the material with tear components.
Clinical Trial: :
Australian New Zealand Clinical Trials Registry, ACTRN12609000230257
Keywords: contact lens • pseudomonas • Staphylococcus