title: Contact lens hydrophobicity and roughness effects on bacterial adhesion.
abstract: OBJECTIVE
  This study was designed to assess whether hydrogel contact lens (CL) surface hydrophobicity and roughness affect Staphylococcus epidermidis adhesion.
  
  
  METHODS
  Bacterial adhesion experiments were performed on two unworn silicone hydrogel and three unworn conventional hydrogel CLs using the S.epidermidis strain CECT 4184. Microbial colonization was assessed by conducting counts expressed as colony-forming units. CL hydrophobicity was determined through water contact angle measurements and the roughness parameters such as mean surface roughness (Ra), kurtosis (Rku), and skewness (Rsk) were determined through atomic force microscopy in Tapping Mode.
  
  
  RESULTS
  The conventional CLs showed similar water contact angles (p > 0.05) and were classified as hydrophilic. The silicone hydrogel CLs yielded hydrophobic contact angles with no significant differences between them (p > 0.05). The lenses with the highest (nelfilcon A and ocufilcon B) or lowest (comfilcon A and omafilcon A) Ra values displayed a lesser or greater extent of spikiness of their surfaces, respectively. All lenses showed a predominance of peaks (Rsk > 0) over troughs. S. epidermidis adhered more to the hydrophobic CLs (p < 0.05). Omafilcon A and comfilcon A, which showed the lowest Ra values among the hydrophilic and hydrophobic lenses, respectively, returned the lowest bacterial adhesion scores (p < 0.05).
  
  
  CONCLUSIONS
  Our results suggest that more hydrophobic CLs are more prone to S. epidermidis adhesion. Although the Ra appears to be related to S. epidermidis adhesion, the influence of Rku and Rsk on this variable remains unclear.
authors.affiliation: Departments of Applied Physics, University of Santiago de Compostela, Santiago de Compostela, Spain. mjesus.giraldez@usc.es
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Giraldez
authors.forename: Carlos Garcia
authors.initials: CG
authors.lastname: Resua
authors.forename: Madalena
authors.initials: M
authors.lastname: Lira
authors.forename: M Elisabete C D Real
authors.initials: ME
authors.lastname: Oliveira
authors.forename: Beatriz
authors.initials: B
authors.lastname: Magariños
authors.forename: Alicia E
authors.initials: AE
authors.lastname: Toranzo
authors.forename: Eva
authors.initials: E
authors.lastname: Yebra-Pimentel
mesh_terms: D001422:Bacterial Adhesion; D003261:Contact Lenses / Q000009:adverse effects / Q000382:microbiology*; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects / Q000382:microbiology*; D003902:Detergents; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D018625:Microscopy, Atomic Force / Q000379:methods; D012828:Silicones; D013212:Staphylococcus epidermidis / Q000502:physiology*; D013499:Surface Properties; D014867:Water
chemical_list: D003902:Detergents; D012828:Silicones; D014867:Water; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate