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L. Liu, L. Jones, H. Sheardown; Wetting Agent Release From Contact Lenses . Invest. Ophthalmol. Vis. Sci. 2005;46(13):908.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: End of day dryness is a major complaint of contact lens wearers. One potential solution is to incorporate ophthalmic compatible wetting agents into the contact lens matrix. The slow release of the incorporated wetting agents will provide a continuously wetted surface, reducing end of day discomfort. Methods: Polyvinyl pyrrolidone (PVP), hyaluronic acid (HA) and dextran were incorporated during curing of PVA based daily wear contact lenses. Wetting agents of different molecular weights were used to investigate the effect of molecular weight on the release profiles. The incorporation process, release kinetics and surface wettability of the lenses were studied. Release was monitored by UV spectrophotometry. Water contact angles at different release times were measured to test surface wettibility. Transparency of lens materials was examined by scanning the sample between 300–700nm using UV–visible spectrophotometry. Results:0.5% to 20% wt/wt (wetting agent/lens formulation) of the wetting agents were introduced into the contact lens matrix. Materials containing PVP showed relatively rapid release, with a plateau within 20 hours followed by slow release for another 50–70 hours. This was likely due to the lower molecular weight and flexible nature of the polymer chains. The release percent increased with the increasing of percent of incorporated wetting agent. Dextran and HA demonstrated more sustained release, with release plateaus after 40 hrs. Contact angle results over 72 hours indicated an improvement in surface wettibility independent of wetting agent. While the incorporation of HA and PVP into the lenses did not alter the transparency, dextran incorporation significantly decreased transparency. Conclusions:Wetting agents were successfully incorporated in contact lenses. Release resulted in significant decreases in the contact angles over 72 hours with all wetting agents. Given the release profiles and the transparency measurements, HA showed the most promise for improving the wetting properties of the lenses.
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