Mechanical characterization of contact lenses

POLY 376

Gang Duan, gd8g2@umr.edu1, Kai-tak Wan, wankt@umr.edu1, and Nathan Ravi2. (1) Department of Mechanical Engineering, University of Missouri-Rolla, 1870 Miner Circle, Rolla, MO 65409-0050, (2) Department of Surgery and Medical Research, VA Medical Center, 915 North Grand Boulevard, Saint Louis, MO 63106
Mechanical properties of soft contact lenses are significant not only in processing and manufacturing, but also in handling and wear. Present techniques usually utilize strips of contact lens material in a tensile tester. We used two alternative techniques to determine the mechanical properties of a soft contact lens. In one technique, a universal probe tester (Nanobionics MTS, MN) was used to indent a contact lens submersed in water. In another case, the contact lens was compressed between parallel plates (DMA7e, Perkin Elmer). From the force displacement curves of these two tests with their corresponding theoretical foundations, the elastic moduli were determined to be 1.960.20 X 105 Pa, and 1.860.18 X 105 Pa. The results were statistically similar, and consistent with published literature. Viscoelastic characterization is in progress.