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Holly Lorentz, Giuliano Guidi, Lyndon Jones, Heather Sheardown; Lipid Adherence to Model Contact Lens Materials. Invest. Ophthalmol. Vis. Sci. 2013;54(15):512.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to analyze the impact of incorporating novel hydrophilic substances into silicone materials and their impact on cholesterol (CH) and phosphatidylcholine (PC) deposition using radiochemical analysis.
Thirteen model lens materials were created based on combinations of dimethylacrylamide (DMAA), hydroxyethyl methacrylate (HEMA) and methacryloxypropyltris(trimethylsiloxy)silane (TRIS). The materials were prepared with and without the incorporation of a hydrophilic novel substance such as hyaluronic acid, alginate, and a silicone surfactant. The model materials were hydrated and advancing contact angles were measured using the sessile drop technique. All materials were incubated in a complex artificial tear solution (ATS) containing protein, lipid, mucin and a trace amount of either 14C-CH or 14C-PC for 3 and 14 days. All materials were then extracted, processed and masses of deposition were quantified (ng/disc) using standard calibration curves.
For the HEMA-based materials tested, only the materials that incorporated the silicone surfactant and alginate showed a statistically significant increase in wettability (p<0.05) over the controls by decreasing the contact angle from 90.8° for the HEMA-TRIS control down to 12.7° for the surfactant HEMA-TRIS material and 60.9° the alginate HEMA-TRIS material. For the DMAA-TRIS materials only the silicone surfactant material showed an improvement in material wettability (p<0.001) with a contact change from 97.1 to 48.2°. For lipid deposition, the incubation time in the ATS had a significant impact on deposition (p ≤0.001) with the 14 day incubations depositing up to 3.4x more lipid than the 3 day incubations. No statistically significant decreases in deposition were seen for any material which incorporated the hydrophilic substance when compared with the controls. However, there were some statistically significant increases in CH and PC deposition (p<0.05) when compared to the corresponding controls, especially for the HEMA-TRIS surfactant containing materials.
Despite the incorporation of hydrophilic substances, such as hyaluronic acid, alginate, and silicone surfactants, into HEMA-TRIS and DMAA-TRIS materials, no reductions in CH and PC deposition were found.
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