Quantification of contact lens wettability after prolonged visual device use under low humidity conditions

Purpose : Discomfort complaints remain the major cause of contact lens drop out despite the growth of the daily disposable (DD) modality and the advent of many new materials. Loss of comfort is associated with longer wearing time, demanding visual tasks, and dry environments. In order to better understand the problem, this study investigated the impact of challenging conditions on wettability of current DD contact lenses. Methods : Habitual DAILIES®TOTAL1® (DT1, n=29) and clariti®1day (c1d, n=31) DD wearers were tested with their habitual lenses and with MyDayTM (MD) and 1-DAY ACUVUE® TruEye® (TE) DD lenses. Digital videos were captured using non-invasive Tearscope illumination after 3 hrs of conventional wear and a subsequent 3 hrs of computer use in a controlled environment of 20% humidity (20%H), with each lens type. The Tear Film Kinetics (TFK), non-invasive break up time (NIBUT) and minimum protected area (MPA) of the lens surface by the tear film, were analyzed over the entire interblink period post hoc by masked investigators. Results : For habitual DT1 wearers, NIBUT was similar after 3 hrs of wear with all lens types, but longer after exposure at 20%H with DT1 than with MD and TE (Mean: DT1 9.2s, MD 6.3s, TE 5.1s; p = 0.052 and p = 0.006 respectively; upper confidence limit = 0.03). The greatest difference in MPA between lenses was after 20%H with DT1 achieving greater protection than MD and TE (Mean DT1 95.4%, MD 84.4%, TE 83.0%, p = 0.002 and p < 0.001 respectively; upper confidence limit < 0). For habitual c1d wearers, TFK were similar for all lens types with the exception of greater MPA for c1d and MD than for TE after 20%H (c1d 89.0%, MD 88.4%, TE 76.2%, p = 0.001 and p = 0.002 respectively). Conclusions : Quantification of the TFK after prolonged, intense visual device use under controlled low humidity conditions is a highly discriminant methodology that can be used to differentiate between in vivo contact lens wettability of different contact lenses. The technique allows quantification of the resistance of the surface to dehydrate under demanding wear conditions, which are more representative of wearing conditions associated with the greatest symptomatology. This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016