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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.
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