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Proceedings Paper

White light optical profiling to unworn contact lenses surface topography analysis
Author(s): M .J. Giraldez; C. Garcia-Resua; M. E. Real Oliveira; C. Sánchez-Sellero; E. Yebra-Pimentel
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Paper Abstract

Purpose: White light optical profiling (WLOP), no usually applied to contact lenses (CL), is a well-established technique for non-contact measurement of surface topography over large areas at moderate lateral and high vertical resolution (sub-nanometer). The aim of this study is to analyze surface properties of five hydrogel CL evaluating representative roughness parameters as Roughness Average (Ra) and Root-Mean-Square Roughness (Rq), that depend on the sampling length, obtained by WLOP. Methods: Lenses used in this study were two highly biocompatible CL and three silicone-hydrogel CL. Unworn CL surface roughness and topography were studied with WLOP (Wyco NT1100) in VSI mode (Vertical Scanning Interferometry). 50X and 20X objectives were used. Height roughness parameters Ra and Rq were calculated for 625, 2500, 10829 and 67646 μm2 areas using the WycoVision®32 analytical software package. Results: High quality 3D topographic images were recorded at randomly different surface locations. Surface topography and Ra and Rq show different values depending on the contact lens and the measurement areas, with the highest roughness scores in biocompatible CL (Ra/Rq for 625, 2500, 10829 and 67646 μm2 areas were: Hioxifilcon 31,04/40,07 - 32,88/44,94 - 42,26/61,54 and 47,88/63,24; omafilcon A 17,61/22,41 - 22,18/28,20 - 49,84/65,98 and 67,12/89,37; senofilcon A 14.47/18,65 - 14,79/18,84 - 12,62/16,09 and 35,93/46,61; comfilcon A: 9,58/11,93 - 14,70/18,42 - 12,17/16,21 and 38,81/51,13; balafilcon A: 7,60/9,69 - 16,30/20,84/ - 9,77/12,83 and 24,19/32,09). Higher roughness parameters were obtained for larger areas in all lenses. Conclusions: Highly biocompatible CL presented the highest roughness surface. WLOP provides useful information about contact lens surface measuring larger areas than other techniques used before.

Paper Details

Date Published: 26 July 2011
PDF: 6 pages
Proc. SPIE 8001, International Conference on Applications of Optics and Photonics, 80013A (26 July 2011); doi: 10.1117/12.891952
Show Author Affiliations
M .J. Giraldez, Univ. de Santiago de Compostela (Spain)
C. Garcia-Resua, Univ. de Santiago de Compostela (Spain)
M. E. Real Oliveira, Univ. do Minho (Portugal)
C. Sánchez-Sellero, Univ. de Santiago de Compostela (Spain)
E. Yebra-Pimentel, Univ. de Santiago de Compostela (Spain)

Published in SPIE Proceedings Vol. 8001:
International Conference on Applications of Optics and Photonics
Manuel Filipe Costa, Editor(s)

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