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N. Ravi, P. D. Hamilton, M. Reilly; Characterization of a New Nanocomposite Projected as an Accommodative Lens Refilling Material. Invest. Ophthalmol. Vis. Sci. 2007;48(13):980.
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We are continuing our search for a lens refilling material closely matching the natural lens in several important parameters, including: Elastic Modulus (E), Refractive Index (RI) Density (ρ) relaxation time constants (τ) and dimensional stability. In this abstract, we describe the characteristics of a new composite formulation in regards to the above parameters.
A water soluble polymer/hydrogel capable of forming a non-swelling gel at low concentrations was gelled at three concentrations in phosphate buffered saline (PBS), with and without the presence of a nanoparticle at two different concentrations. Elastic modulus values were determined using a DMA7e (Perkin Elmer). Refractive Index values were obtained from an Abbe Refractometer and density values were from a Sartorius balance density kit. Time constants were measured from a force decay model using a custom made mechanical indenter.
Measured parameters are displayed in the table.
We are presently using pig lenses as a comparison for our gels. We have aimed for a higher RI, similar to that of human lenses. From our data, we are able to cover the range of the modulus of a youthful lens, and also match the desired refractive index. Density of the material is slightly higher, and the time constants are faster than natural lens material. Nanoparticle loading significantly increased the elastic modulus. Gels without nanoparticle loading were left in PBS for weeks, and showed no dimensional changes after gelling. This material has potential for use in our modeling studies, and will be used for lens refilling studies in the near future.
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