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Katarzyna A. Wygladacz, Daniel J. Hook, Mohinder Merchea, E. Peter Maziarz; Visualization of Hyaluronic Acid Contact Lens Surface Coverage Using DIC and Confocal Imaging. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4730.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate the presence of hyaluronic acid (HA) on the surface of silicone hydrogel (SH) lenses. HA is used in conjunction with a surfactant system in a unique multi-purpose solution (MPS) for improved hydration and wettability on SH lenses characterized with hydrophilic and hydrophobic domains. HA networks adsorbed to SH lenses were visualized using confocal and differential interference contrast (DIC) microscopy and a dye selective for HA (Safranin).
SH contact lenses (Senofilcon A and Balafilcon A) were soaked for 4 hours with an HA containing commercially available MPS (Biotrue). Lenses were then soaked in 3mL of Safranin solution for 3min. Samples were then rinsed with HPLC grade water for 3min to remove unbound dye. Samples were imaged using an Olympus Confocal Laser Scanning Microscope (CLSM) equipped with Differential Interference Contrast (DIC) attachment. Individual confocal images were captured using an air objective (NA 0.75) sequentially across the sample. Images were then combined using fiducial marks for image mosaic stitching. SH lenses incubated with Safranin solution but not exposed to MPS (Biotrue) were characterized as control samples.
Confocal and DIC imaging demonstrated direct visualization of HA networks adsorbed over the entire surface of SH lenses soaked for 4 hours in a HA containing MPS. HA surface coverage was observed for both SH lens material and MPS combinations studied. The control lenses demonstrated no surface modification by HA networks.
Previous studies have shown HA hydration dynamics and release profiles over 20 hours of simulated wear. Confocal imaging used in this study directly demonstrated that the high molecular-weight HA conditioning agent found in a commercially available MPS (Biotrue) adsorbs consistently across the surface of SH lenses which have hydrophilic and hydrophobic zones. Surface modification of SH lenses for improved hydration may be achieved with natural humectants versus the traditional approach of using only surfactants in MPS.Figure 1: DIC image of: HA networks adsorbed to a SH contact lens surface soaked in Biotrue MPS containing HA (bottom panel), and control lens (top panel).
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