Novel in vitro method to determine pre-lens tear break-up time of hydrogel and silicone hydrogel contact lenses

Purpose: To develop an in vitro model to determine pre-lens non-invasive break- up time (NIBUT) and to subsequently use this method to compare the NIBUT over contemporary daily disposable (DD) contact lenses (CL). Methods: Three silicone hydrogel (SH) and two conventional hydrogel (CH) DD CLs were incubated in an artificial tear solution (ATS). A model blink cell (MBC) was utilised to mimic intermittent air exposure. CLs were repeatedly submerged for 3 seconds (s) and exposed to air for 10 s over periods of 2, 6, 12, and 16 hours (h). NIBUTs (n = 4) were determined out of the blister pack (T-0) and at the end of each incubation period. Results: Overall, nesofilcon A showed the longest NIBUTs (p < 0.001). At T-0, CHs revealed significantly longer NIBUTs (p <= 0.001) than SHs. After 2 h, nesofilcon A showed the longest NIBUT, however, this was only statistically significant compared with delefilcon A (p <= 0.001). After 6 h, nesofilcon A NIBUT was significantly longer than all other CLs (p <= 0.001). Etafilcon A showed a significantly longer NIBUT (p <= 0.001) after 12 h and delefilcon A had the longest NIBUT (p <= 0.001) after 16 h. Statistically significant (p <= 0.05) changes of NIBUT within the lens materials varied between time points. After 16 h, all CLs showed significant reductions in NIBUTs (p <= 0.001) in comparison to T-0. Conclusion: NIBUT values reduced gradually over time and varying levels of deposition impacted measured prelens NIBUTs. While NIBUT of CH materials are longer immediately out of the blister pack, after tear film exposure, the NIBUTs obtained using this methodology became very similar.