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

Purpose: Discomfort of silicone hydrogel (SiHy) contact lenses (CL) is associated with longer wearing time, demanding visual tasks, and dry environments. This study investigated the impact of challenging environmental conditions on thewettability of four daily disposable SiHy CL. Methods: Habitual wearers of delefilcon A (n=32) and somofilcon A (n=32) were tested with their habitual lenses and with stenfilcon A and narafilcon A lenses. Digital videos were captured using non-invasive Tearscope illumination after 3 hrs of conventional wear and 3 hrs of computer use at 20% relative humidity (RH). Masked investigators analysed non-invasive break up time (NIBUT), minimum protected area (MPA) ofthe lens surface by the tear film, and dehydration speed (DS) over the interblink period after exposure to 20% RH.Results: For habitual delefilcon A wearers, mean NIBUT was longer with delefilcon A (9.2 sec) than stenfilcon A (6.3 sec, p = 0.052) and narafilcon A (5.1 sec, p = 0.006); mean MPA was significantly higher with delefilcon A (95.4%)than stenfilcon A (84.4%, p = 0.002) and narafilcon A (82.9%, p = 0.006); mean DS was lower with delefilcon A (0.28 mm2/sec) than stenfilcon A (0.81 mm2/sec, p = 0.002) and narafilcon A (0.60 mm2/sec, p = 0.056). For habitual somofilcon A wearers, mean MPA was lower for narafilcon A (76.2%) than for somofilcon A (89.0%, p < 0.001) but not stenfilcon A (88.4%, p = 0.748) and mean DS was higher for narafilcon A (0.96 mm2/sec) than somofilcon A (0.60mm2/sec, p = 0.029) but not stenfilcon A (0.51 mm2/sec, p = 0.701). Conclusions: Delefilcon A CL performed betterthan stenfilcon A and narafilcon A after 6 hrs of wear including 3 hrs intensive visual tasks under challenging environmental conditions. Delefilcon A CL may be preferable for CL wearers with intensive computers and/or digital devices usage.