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Vivian Chan, Chau-Minh Phan, Lyndon William Jones; Evaluating lysozyme deposition on contemporary daily disposable contact lenses in a novel in vitro blink model. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1496.
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To evaluate total lysozyme deposition on daily disposable (DD) contact lenses (CL) using a novel in vitro eye-blink model.
Three conventional hydrogel (CH) DD CL materials (etafilcon A, omafilcon A, nelfilcon A) and three silicone hydrogel (SH) DD CL materials (delefilcon A, senofilcon A, somofilcon A) were tested. The lenses were removed from their blister packs and placed directly on the eye model. An artificial tear solution (ATS) was flown over the lenses at a flow rate of 1 µl/min. The blink rate was set to 6 blinks per minute and the model was incubated at room temperature (23-26°C) and >45% humidity. After exposure periods of 2, 4 or 8 hours the lenses were removed and the lysozyme was extracted using acetonitrile: 0.2% trifluoroacetic acid (n=3). A separate experiment was conducted with lenses incubated in a vial containing 480 µL of ATS on an orbital shaker at 60 rpm for 8 hours (n=3). The lysozyme activity was measured using a spectrophotometric assay.
Etafilcon A had the highest amount of active lysozyme absorption at all time points (p>0.001). After 8 hours, a cumulative total of 402 ± 102µg/lens of active lysozyme was absorbed on etafilcon A. Delefilcon A had the highest cumulative amount of active lysozyme (26 ± 1µg/lens) for SH materials (p<0.05). Nelfilcon A, senofilcon A and somofilcon A had the lowest amount of lysozyme activity (p<0.05). Overall, CH had a higher amount of lysozyme activity than SH after 8 hours (p>0.05). The amount of active lysozyme sorption for certain lens types was different when measured using the eye-blink model as compared to a vial (p<0.05). Etafilcon A had a higher amount of active lysozyme when incubated on the blink model as compared to the vial (p<0.05), whereas somofilcon A and senofilcon A had a higher amount of lysozyme activity in the vial compared to the eye model (p<0.05). Both methods, however, showed no differences in the amount of active lysozyme sorption for omafilcon A, nelfilcon A, and delefilcon A (p>0.05).
The in vitro eye-blink model provides quantitative data that is close to that determined from ex vivo studies and is an excellent model to assess the deposition of lysozyme on DD CL materials.
This is a 2020 ARVO Annual Meeting abstract.
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