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Development and Preliminary Evaluation of a System to Rapidly Measure Coefficient of Friction on Soft Contact Lenses
International Journal of Ophthalmology & Visual Science
Volume 4, Issue 4, December 2019, Pages: 88-96
Received: Oct. 2, 2019; Accepted: Oct. 22, 2019; Published: Nov. 14, 2019
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Daniel Joseph Hook, Bausch & Lomb Incorporated, Rochester, USA
Charles Phillip Lusignan, Bausch & Lomb Incorporated, Rochester, USA; Department of Physics and Astronomy, Rochester Institute of Technology, Rochester, USA
Katarzyna Aneta Wygladacz, Bausch & Lomb Incorporated, Rochester, USA
Jeffery Merrill Schafer, Bausch & Lomb Incorporated, Rochester, USA
Robert Brian Steffen, Bausch & Lomb Incorporated, Rochester, USA
William Thomas Reindel, Bausch & Lomb Incorporated, Rochester, USA
Gary Michael Mosehauer, Bausch & Lomb Incorporated, Rochester, USA
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This study was undertaken to 1. develop an apparatus to rapidly measure coefficient of friction (COF) on soft contact lenses; 2. determine if COFs measured on two daily-disposable lens models before and after wear are consistent with changes in lens surface morphology observed in parallel atomic force microscopy (AFM) images. Methods: A stress rheometer was adapted to measure COF on a soft contact lens by custom fabrication of a rapid-mount sample stage for increased throughput. Five subjects were randomly assigned to wear daily disposable nesofilcon A and delefilcon A contact lenses bilaterally for 4 hours, after which time lenses were removed. Static and kinetic COFs of lenses worn on left eyes was measured, while lenses worn on right eyes were imaged in parallel by AFM in tapping mode. Root mean square (RMS) surface roughness was calculated for all lenses to determine the effect of wear on surface topography. Results: Both static and kinetic COFs measured on unworn delefilcon A silicone hydrogel lenses were greater than on nesofilcon A traditional hydrogel lenses. Static COF on nesofilcon A increased significantly after wear, while kinetic COF trended higher but did not change significantly. Similarly, static COF on delefilcon A also increased significantly after wear, and kinetic COF trended higher but did not change significantly, both remaining greater than on worn nesofilcon A. Parallel AFM analysis demonstrated that nesofilcon A lenses are smoother than are delefilcon A out of the package. Both lenses attracted deposits during wear, but the nesofilcon A surface was less altered by on-eye wear than was the delefilcon A surface. Conclusion: A system to rapidly measure static and kinetic COFs was successfully developed. Static and kinetic COFs measured on delefilcon A were greater than on nesofilcon A lenses. More deposits and greater surface roughness were observed after wear on delefilcon A relative to nesofilcon A. Parallel AFM images of worn and unworn lenses were not predictive of measured COFs, but increased roughness visible by AFM was consistent with observed increases in COF, although not all increases were statistically significant.
Daily Disposable Contact Lens, Atomic Force Microscopy, Coefficient of Friction, Tribological Measurement Technique
To cite this article
Daniel Joseph Hook, Charles Phillip Lusignan, Katarzyna Aneta Wygladacz, Jeffery Merrill Schafer, Robert Brian Steffen, William Thomas Reindel, Gary Michael Mosehauer, Development and Preliminary Evaluation of a System to Rapidly Measure Coefficient of Friction on Soft Contact Lenses, International Journal of Ophthalmology & Visual Science. Vol. 4, No. 4, 2019, pp. 88-96. doi: 10.11648/j.ijovs.20190404.16
Copyright © 2019 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License ( which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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