Fig. 8. Characterization of physical properties of contact lenses. (a) ND-nanogels can be embedded into polyHEMA gels and cast into contact lenses. (b) ND-nanogel embedded lenses maintain optical transparency. (c) Comparison of average visible light transmittance (400–700 nm) and water content of polyHEMA lenses without additives, with 0.1% (w/w) PEI-chitosan, with 0.1% (w/w) pristine ND, with 0.1% (w/w) ND-nanogel or 0.2% (w/w) ND-nanogel. (d) Tensile stress–strain curves comparing polyHEMA lenses without additives, with 0.1% (w/w) PEI-chitosan, with 0.1% (w/w) pristine ND, with 0.1% (w/w) ND-nanogel or 0.2% (w/w) ND-nanogel. (e) Young's modulus of the polyHEMA lenses without additives, with 0.1% (w/w) PEI-chitosan, with 0.1% (w/w) pristine ND, with 0.1% (w/w) ND-nanogel or 0.2% (w/w) ND-nanogel, as determined by the first 5% of the stress–strain curve slope. Reprinted with permission from ref. 72. Copyright 2014, American Chemical Society.