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H. A. Ketelson, N. Dassanayake, H. Lyon, D. Meadows; In vitro and ex vivo Lipophilic Dye Uptake Into Silicone Hydrogel Lenses. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5419.
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© ARVO (1962-2015); The Authors (2016-present)
To develop a lipophilic dye uptake method to quantitatively measure the in vitro and ex vivo uptake of a lipophilic dye into silicone hydrogel lenses. The partitioning kinetics of the lipophilic dye into the various silicone hydrogel lens types were investigated to facilitate understanding the differences in the lens material lipophilic properties.
A lipophilic dye, Sudan IV, was dispersed in silicone oil and used as a standard solution for the uptake studies. Lenses were taken out of the blister pack and soaked in saline for 24 hours. The lenses used were Acuvue* Advance* (AA), Acuvue* OASYS* (AO), O2OPTIX*(O2O) and PureVision*(PV). After the 24 hour soak, the lenses were transferred to the dye dispersion and soaked for 2 hours. The lenses were removed from the dye solution and rinsed by immersion in physiological saline solution followed by dye extraction with DMSO and analysis by UV/VIS spectroscopy. Kinetic studies were carried out in the same manner but the lenses were soaked for various time periods. Ex vivo measurements were carried out using a pool of 8 normal contact lens wearing patients where the lenses were worn for 8 hrs before removing the lenses from the eyes and analyzing for the lipophilic dye uptake.
The relative differences in lipophilic dye uptake following removal from the manufacturers lens pack were PV >> AA = AO > O2O. The lipophilic uptake into PV lenses was significant compared to the other silicone hydrogel lens materials. The kinetics of dye uptake was followed over a 24 hour period with PV showing a trend towards increasing dye uptake even after 24 hours. The dye uptake for the AA, AO and O2O lenses appeared to plateau after 24 hours. Although the PV and O2O lenses are surface modified there was no apparent correlation of the lipophilic dye uptake to lens surface modification. The ex vivo data showed the following uptake differences where AA > PV > O2O. The differences in ex vivo uptake compared to the in vitro data were believed to be a reflection of the variation in tear component interaction to the different lens materials.
This study demonstrated that the lipophilic uptake of a dye can be used to quantitatively differentiate the in vitro and ex vivo lipophilic character of silicone hydrogel lenses. This measurement method can generate valuable information regarding the silicone hydrogel material property differences and may help to provide insight into the various contact lens phenomena observed in published studies including lipid and biocide uptake, bacterial adhesion and lens wettability.*Trademarks are the properties of their respective owners.
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