Abstract
Purpose: :
Bacterial adhesion to intraocular lenses (IOL) is the essential step in the pathogenesis of postoperative endophthalmitis. The first phase of bacterial adhesion to a substratum is an instantaneous physical phase dictated by a number of physico-chemical variables. Important parameters to describe the surface properties are the contact angle and surface free energy. We report a new method to determine the dispersive and Acid-Base components of the surface free energy of different IOL surfaces.
Methods: :
The present study was performed with IOLs made of six different polymeric materials (PMMA, HSM PMMA, Silicone, Hydrophilic acrylic, Hydrophobic acrylic and Collamer). The contact angle measurements were carried out using the Digidrop goniometer. The contact angle was measured at the end of wetting stage of the surface by the drop, according to the Van Oss procedure. The surface free energy of intraocular lenses was determined from contact angles measurements, using the three different approaches of Fowkes, Owens-Wendt and Good-Van Oss.
Results: :
The IOL surface free energy values determined with the three different approaches (Fowkes, Owens-Wendt and Good-Van Oss) were consistent. Discrepancies were found between these values and those obtained with the Zisman model, widely used. The 3 different theoretical approaches indicated that the six studied IOLs can be separated in dispersive implants (Silicone) and in monopolar or bipolar implants (Hydrophobic acrylic, PMMA, Collamer, Hydrophilic acrylic, HSM-PMMA).
Conclusions: :
Contact-angle measurements and surface free energy calculations differ depending on the theoretical approach. Proper choice is of major importance to have useful information about the material surface and its potential biomaterial interactions.
Keywords: intraocular lens • endophthalmitis