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C. Maldonado–Codina, P.B. Morgan; In vitro Wettability of Silicone Hydrogel Contact Lenses Determined Using the Sessile Drop Technique . Invest. Ophthalmol. Vis. Sci. 2006;47(13):81.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the in vitro wettability of silicone hydrogel contact lenses by measuring their contact angles.
Contact angles were measured using the sessile drop technique with an OCA 20 instrument (DataPhysics Instruments GmbH, Filderstadt, Germany). The following lens types were used: PureVision (Bausch & Lomb), Focus Night & Day (Ciba Vision), O2 Optix (Ciba Vision), Acuvue Oasys (Johnson & Johnson) and Acuvue Advance (Johnson & Johnson). The probe liquid used was deionized water. The lenses were investigated under two conditions – straight from their packaging solutions (surface active ingredients present) and after soaking in saline for 48 hours (surface active ingredients absent). Three lenses of each type were used for each condition and each lens type was assessed three times by analysing five frames over a 10 second movie clip. A three factor repeated measures ANOVA was carried out with lens type, lens run and condition being the factors of interest.
Contact angles were higher in lenses soaked in saline compared to lenses straight from the packaging solution (p = 0.0001). The first lens run carried out produced lower contact angles than second and third lens runs (p = 0.02). Contact angles for all lenses were significantly different from each other (p = 0.0001) except for Acuvue Advance and Acuvue Oasys. Sessile equilibrium contact angles (degrees) for lenses straight from the blister packaging were as follows (mean ± SD): PureVision, 93.6 ± 2.9, Acuvue Oasys, 78.7 ± 9.5, Acuvue Advance, 65.6 ± 6.4, O2 Optix, 44.4 ± 6.4 and Focus Night & Day, 43.9 ± 6.1. Sessile equilibrium contact angles for lenses pre–soaked in saline were as follows: PureVision, 101.6 ± 6.2, Acuvue Advance, 96.3 ± 13.5, Acuvue Oasys, 85.0 ± 9.0, Focus Night & Day, 43.9 ± 5.5 and O2 Optix, 37.2 ± 8.3.
Surface active ingredients present in the blister lowered the contact angle of the lenses investigated. All lenses investigated were significantly different from each other except for Acuvue Advance and Acuvue Oasys. The methodology used here is sensitive to dehydration effects which may be overcome by using a humidity chamber.
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