title: Wear effects on microscopic morphology and hyaluronan uptake in siloxane-hydrogel contact lenses.
abstract: The purpose of this study was a comparison between new and worn siloxane-hydrogel contact lenses in terms of microscopic structure, surface morphology, and loading of hyaluronan. The analyses were performed by scanning electron microscopy, with the support of the freeze-drying technique, and by fluorescence confocal microscopy. Along the depth profile of new lenses, a thin porous top layer was observed, which corresponds to the region of hyaluronan penetration inside well-defined channels. The time evolution was followed from one day to two weeks of daily wear, when a completely different scenario was found. Clear experimental evidence of a buggy surface was observed with several crests and regions of swelling, which could be filled by the hyaluronan solution. The modifications are attributed to the progressive relaxation of the structure of the polymeric network.
authors.affiliation: Materials Science Department, University of Milano Bicocca, via Cozzi 55, I-20125, Milan, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Tavazzi
authors.affiliation: Materials Science Department, University of Milano Bicocca, via Cozzi 55, I-20125, Milan, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Tonveronachi
authors.affiliation: Materials Science Department, University of Milano Bicocca, via Cozzi 55, I-20125, Milan, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Fagnola
authors.affiliation: Materials Science Department, University of Milano Bicocca, via Cozzi 55, I-20125, Milan, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Cozza
authors.affiliation: Materials Science Department, University of Milano Bicocca, via Cozzi 55, I-20125, Milan, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Ferraro
authors.affiliation: Materials Science Department, University of Milano Bicocca, via Cozzi 55, I-20125, Milan, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Borghesi
authors.affiliation: Interdepartmental Center of Advanced Microscopy, CIMA, University of Milan, via Celoria 26, I-20133, Milan, Italy.
authors.forename: Miriam
authors.initials: M
authors.lastname: Ascagni
authors.affiliation: DeFENS, Department of Food, Environmental and Nutritional Sciences, Packaging Division-University of Milan, Via Celoria 2, I-20133, Milan, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Farris
mesh_terms: D003263:Contact Lenses, Hydrophilic; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D008422:Materials Testing; D012833:Siloxanes / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D020100:Hydrogels; D012833:Siloxanes; D006820:Hyaluronic Acid
keywords: contact lens; freeze-drying; hyaluronan; scanning electron microscopy; siloxane-hydrogel