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Purpose: This study was designed to develop a novel technique called non-invasive keratograph dry-up time (NIK-DUT), which used an adapted corneal topographer, to analyse in-vitro contact lens surface dewetting and the effects of combinations of lenses and lens care solutions on dewetting., Methods: Variables were assessed to optimise sensitivity and reproducibility. To validate the method, in-vitro dewetting of silicone hydrogel contact lenses (balafilcon A, comfilcon A, lotrafilcon A, lotrafilcon B and senofilcon A) was tested. All lens types were soaked in OPTI-FREE ® PureMoist ® Multipurpose Disinfecting Solution (OFPM) and Sensitive Eyes ® Saline Solution. The mean NIK-DUT, defined as drying of 25% of the placido ring measurement segments (NIK-DUT_S25), was calculated for each lens/lens solution combination and a visual map constructed representing the time and location of the dry-up event., Results: Optimal conditions for NIK-DUT measurement included mounting onto a glass stage with a surface geometry of r=8.5mm, e=0, and measuring with high intensity red or white illumination. This method detected significant differences in contact lens dewetting with different lens soaking solutions. NIK-DUT_S25 for all lenses was longer when pre-soaked in OFPM versus saline. Visual analysis showed that dewetting of contact lenses was not uniform across surfaces and differed between test solutions., Conclusions: NIK-DUT is suitable for detecting differences in dewetting among various contact lenses and lens-care combinations. NIK-DUT can quantify the dewetting of large areas of lens surfaces with little subjective influence. Lens care solutions containing surface-active wetting agents were found to delay surface dewetting of silicone hydrogel lenses., (Copyright © 2017. Published by Elsevier Ltd.)

Sebastian Marx,1 Julia Eckstein,1 Wolfgang Sickenberger1,2 1JENVIS Research c/o Ernst-Abbe University of Applied Sciences Jena, Jena, Germany; 2Department of Optometry & Vision Science, Ernst-Abbe University of Applied Sciences Jena, Jena, GermanyCorrespondence: Sebastian MarxJENVIS Research c/o Ernst-Abbe University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, Jena 07745, GermanyEmail s.marx@jenvis-research.comPurpose: The primary objective of this study was to evaluate the in vivo pre-lens non-invasive drying-up time of two types of daily disposable contact lenses (DDCLs) after 12 hours of wear.Methods: This prospective, randomized, single-center, cross-over pilot study evaluated 31 subjects aged 18– 44 years with normal eyes and good tear film stability who were adapted current soft contact lens wearers. Subjects wore nelfilcon A and stenfilcon A DDCLs for 12 hours each on two different days. Non-invasive video keratography drying-up time (NIK-DUT) videos of each eye were recorded 12 hours after lens insertion for about 25 seconds, with a 5-minute tear film recovery time allowed between video recordings of the right and left eyes to avoid bias. Post-blink time required to reach 15% distortion of the projected rings and the speed of break-up at 15 seconds post-blink were measured at each time point and on-eye wettability was determined by ring mire projection under white light illumination.Results: Mean time to reach 15% ring distortion was similar for nelfilcon A (19.25± 3.20 sec) and stenfilcon A (20.24± 3.02 sec) DDCLs but varied highly among subjects. The mean speed of break-up at 15 sec post-blink was 0.3± 0.38% distortion/sec (95% confidence interval [CI] 0.138– 0.365% distortion/sec) for nelfilcon A and 0.2± 0.23% distortion/sec (95% CI 0.048– 0.279% distortion/sec) for stenfilcon A DDCLs.Conclusion: Multifunctional topography allowed the objective evaluation of in vivo pre-lens tear film stability using ring mire projection. This dynamic method was simple, fast and non-invasive, enabling measurements of NIK-DUT and evaluating wettability over a large area, greater than the optical zone of the contact lens surface, for the entire inter-blink interval.Keywords: pre-lens tear film stability, wettability, daily disposable contact lenses, non-invasive break-up time, non-invasive drying-up time, corneal topography