Abstract
Purpose: :
The aim of this study was to analyze how hydrogel contact lenses roughness parameters affect to bacterial adhesion. So, surface properties of four hydrogel contact lenses were determined by AFM and related with Sthaphylococcus adhesion.
Methods: :
The lenses used in this study were two high water content hydrogel lenses: Hioxifilcon and Omafilcon A; and two silicon hydrogel lenses: Senofilcon A and Confilcon A. Unworn contact lenses surfaces roughness and topography were studied by AFM (Veeco, multimode-nanoscope V) in tapping modeTM. Roughness measurements Ra and Rq for 25 and 196 µm2 areas were determined using the WycoVision®32 analytical software package. Each contact lens was immersed in 1 ml of a cell suspension of Staphylococcus Epidermis CECT 4184. Initial concentration, 1.2x109 colony-forming units (CFU/ml), was determined by dilution of the suspension in steril saline solution and spread onto TSA-1 plates. After incubating lenses in this solution for 2 hours at 37ºC, washing and sonication CFUs were enumerated. Four measurements were done.
Results: :
High-quality images of contact lens surfaces were obtained. Surface topography and roughness parameters show different characteristics depending on the own nature of the contact lens (table 1). CFUs (mean ± SD) determined in contact lenses are shown in table 2. Higher CFUs value was observed in Senofilcon A contact lens.
Conclusions: :
High water contact lenses exhibit significantly lower bacterial adhesion in vitro than silicon hydrogel ones. Contact lenses roughness surface could be in relation with sthaphylococus adhesion as both silicon hydrogel contact lens and high water content hydrogel contact lens with higher Ra and Rq values show the highest CFUs value. Differences in CFUs values between both silicon and high water content hydrogel contact lenses could be due to polymer differences between lenses.
Keywords: contact lens • Staphylococcus • imaging/image analysis: non-clinical