Encontrados 5 documentos, a visualizar página 1 de 1
Surface AFM microscopy of unworn and worn samples of silicone hydrogel contact ...
González-Méijome, José Manuel; López-Alemany, António; Almeida, José B.; Parafita, Manuel A.Abstract: Purpose. To evaluate the qualitative and quantitative topographic changes in the surface of worn contact lenses (CLs) of different materials using atomic force microscopy (AFM). Methods. The topography of five different CL materials was evaluated withAFM over a surface of 25 lm2 according to previously published experimental setup. Average roughness (Ra) and root mean square (Rms) values were obtained...
Qualitative and quantitative characterization of the in vitro dehydration proce...
González-Méijome, José Manuel; López-Alemany, António; Parafita, Manuel A.; Almeida, José B.; Refojo, Miguel F.PURPOSE: To investigate the in vitro dehydration process of conventional hydrogel and silicone-hydrogel contact lens materials. METHODS: Eight conventional hydrogel and five silicone-hydrogel contact lenses were dehydrated under controlled environmental conditions on an analytical balance. Data were taken at 1-min intervals and dehydration curves of cumulative dehydration (CD), valid dehydration (VD), and dehyd...
Oxygen transmissibility of piggyback systems with conventional soft and silicon...
López-Alemany, António; González-Méijome, José Manuel; Almeida, José B.; Parafita, Manuel A.; Refojo, Miguel F.To investigate the apparent oxygen transmissibility of various piggyback systems using conventional and silicone hydrogel soft contact lenses of different water content and permeability, rigid poly(methyl methacrylate), and rigid gas-permeable lenses of medium, high, and ultrahigh oxygen permeability. The aim of the study was to establish which material (rigid or hydrogel) is more representative of the resultin...
Equivalences between refractive index and equilibrium water content of conventi...
González-Méijome, José Manuel; López-Alemany, António; Lira, Madalena; Almeida, José B.; Oliveira, M. Elisabete; Parafita, Manuel A.PURPOSE: The purpose of the present study was to develop mathematical relationships that allow obtaining equilibrium water content and refractive index of conventional and silicone hydrogel soft contact lenses from refractive index measures obtained with automated refractometry or equilibrium water content measures derived from manual refractometry, respectively. METHODS: Twelve HEMA-based hydrogels of differen...
Correlations between central and peripheral changes in anterior corneal topogra...
González-Méijome, José Manuel; Sañudo-Buitrago, Francisco; López-Alemany, António; Almeida, José B.; Parafita, Manuel A.PURPOSE: To investigate the changes in central and peripheral anterior corneal curvatures after myopic laser in situ keratomileusis (LASIK) and to correlate them with the manifest refractive change to discuss how such results could affect post-LASIK corneal topography profiles and midterm stability and their implications in postsurgical contact lens fitting. METHODS: Topographic and refractive data from 18 eyes...
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