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M.A. Princz, L.W. Jones, H. Sheardown; Release of Wetting Agents From Nelfilcon Contact Lenses . Invest. Ophthalmol. Vis. Sci. 2005;46(13):907.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The release of various wetting agents from a hydrogel contact lens material was examined to assess whether the use of different wetting agents could be used to improve patient comfort with daily wear soft contact lenses. Methods: Nelfilcon A (CIBA Vision Focus DailiesTM) contact lenses were swollen in varying concentrations of 2500 and 10000 MW polyvinyl pyrrolidone (PVP), as well as high concentrations of carboxymethyl cellulose (CMC), hyaluronic acid (HA) and dextran (10K and 40K MW) in different solvents at room temperature for 24 hours. The solvents included Milli–Q water, PBS and varying dilutions of ethanol in Milli–Q water. Release was measured by soaking the lenses in phosphate buffer solution (PBS) followed by UV–Vis spectrophotometry or fluorometric analysis. Advancing and receding sessile drop contact angles and swelling studies were also performed. Results: First order release profiles were observed for all wetting agents. Little, or no release of PVP, CMC and dextran were observed after 1.5 hours, while HA was released from the lenses for more than 4 days. Swelling in ethanol solutions resulted in a slightly greater solvent uptake and presumably an increased amount of the wetting agent in the lens. Incorporation and release of PVP initially decreased contact angles but water contact angles returned to values equal to control contact angles within the first hour of sampling. Conclusions: These results suggest that high molecular weight compounds may be released from contact lenses for clinically useful wear periods, potentially improving the comfort of hydrogel lenses. The water contact angle results suggest that release of the wetting agents during the period of wear will improve the wettability of the lenses.
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