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J. W. Davis, H. A. Ketelson, A. Shows, D. L. Meadows; A Lens Care Solution Designed for Wetting Silicone Hydrogel Materials. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3417.
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© ARVO (1962-2015); The Authors (2016-present)
To determine contact angles on silicone hydrogel (SiH) lenses using a modified captive bubble (CB) technique and the sessile drop (SD) method. SiH lenses pre-soaked with a novel lens care solution (LCS) containing a di-block copolymer designed for wetting SiH lenses were studied. Complementary measurements to characterize the bulk hydrophobicity of the SiH lenses following soaking in the LCS are reported using a lipophilic dye diffusion technique.
A CB method was modified and coupled to an optical device fitted with a video camera and lens curve fitting software to obtain the contact angles. A modified lens support and syringe to hold the bubble upright was designed and used to generate the advancing and receding bubbles. A lipophilic dye, Sudan IV, was dispersed in silicone oil and used as a standard solution for the dye diffusion studies. Dye extraction was done with DMSO and analysed by UV/VIS spectroscopy. Acuvue® AdvanceTM (AA), Acuvue® OASYSTM (AO), O2OPTIXTM (O2O), PureVision® (PV), BiofinityTM (BF) lenses were used in the studies and were compared with lenses presoaked in the LCS.
The SD and CB methods showed that SiH lenses pre-soaked with the LCS lowered the advancing contact angles for PV by 92% and 78%, respectively, compared to the lens controls (out of pack). For AO lenses the angles were lowered by 94% and 33%, respectively. The bulk hydrophobicity properties of the lenses were shown to decrease following exposure to the LCS. For example, the lipophilic dye uptake decreased by 54% and 67% for the PV and AO lenses, respectively. This showed the LCS decreased the hydrophobicity of the SiH lenses.
This study indicated that both the SD and CB methods can be used to characterize the wettability of SiH lens materials. Since SiH lens materials have varying bulk and surface chemistry properties it was found that both methods could be used to assess the lens wetting phenomena occurring under different environmental conditions. Specific physico-chemical interactions were shown to occur between the di-block copolymer in the LCS and the SiH lenses. Significant improvements in the wettability and hydrophilization of the silicone hydrogel materials were observed using the novel LCS.
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