Photocrosslinkable hyaluronic acid as an internal wetting agent in model conventional and silicone hydrogel contact lenses

Photocrosslinkable methacrylated hyaluronic acid (HA) was prepared and incorporated into model conventional and silicone hydrogel contact lenses as an internal wetting agent. The molecular weight of the HA, the degree of methacrylation as well as the amount (0.25 to 1.0 wt %) incorporated were varied. The HA-containing hydrogels were analyzed using a variety of techniques including water contact angles, equilibrium water content (EWC), and lysozyme sorption. The presence of HA could be detected in the materials using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy-attenuated total reflectance. The materials containing methacrylated HA had improved hydrophilicity and reduced lysozyme sorption. Effects of modified HA on EWC were dependent upon the materials but generally increased water uptake. Increased mobility of the HA associated with a lower molecular weight and lower degree of methacrylation was found to be more effective in improving hydrophilicity and decreasing lysozyme sorption than the less mobile HA. All results found suggest that photocrosslinkable HA has significant potential in contact lens applications.