Evaluating the initial and end-of-day wettability of contemporary daily disposable contact lenses using various in vitro methods.
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SIGNIFICANCE: Contact lens wettability is potentially correlated with friction, which is linked to lens comfort. However, measuring wettability can be highly variable. This study assessed wettability using three techniques for a more accurate profile. PURPOSE: To evaluate the wettability of contemporary daily disposable contact lenses after 16 hours on an in vitro model using the sessile drop, captive bubble, and a novel in vitro noninvasive keratograph breakup time (NIKBUT) method. METHODS: The wettability of six contemporary silicone hydrogel contact lens materials (verofilcon A, delefilcon A, senofilcon A, kalifilcon A, stenfilcon A, and somofilcon A) and two conventional hydrogel materials (nesofilcon A and etafilcon A) were evaluated using an in vitro blink model at t = 0 and 16 hours. The blink rates of the eye model were 20 blinks per minute. Sessile drop and captive bubble angles were analyzed using the Optical Contact Analyzer. NIKBUT was assessed on a blink model in combination with the OCULUS Keratograph 5M. RESULTS: There were no significant differences in wettability for any lens types between 0 and 16 hours when assessed using the captive bubble or NIKBUT methods (p>0.05). For the sessile drop method, verofilcon A had the lowest contact angle values (36.5 ± 2.9°), and all lenses except for etafilcon A had similar wettability after 16 hours. All the lenses had similar wettability when assessed using the captive bubble method, suggesting that they had similar wettability under optimal wetting conditions. For NIKBUT, delefilcon A had the longest NIKBUT values (9.0 ± 1.0 s) after 16 hours. CONCLUSIONS: The sessile drop technique produced the most measurable differences in wettability between different lens types, whereas the captive bubble technique was not able to provide any measurable differences between lenses. NIKBUT measurements may provide a better measure of on-eye wettability, but variability in the results using the current eye model still needs to be addressed in future studies for improved repeatability. Although the contact lenses showed different contact angles and NIKBUT results, their in vitro wettability did not significantly change over the 16 hours of simulated wear in terms of the captive bubble or NIKBUT values.
