Mechanically Enhanced Soft Contact Lenses from Photodimerization Cross-Linking

In this study, we synthesized three novel acrylic monomers with a cinnamate group. We then mixed each monomer with 2-hydroxyethyl methacrylate (HEMA) to prepare soft contact lenses through bulk polymerization. Fourier transform infrared (FT-IR) and UV spectral analyses confirmed that the cinnamate group in the polymer undergoes a photodimerization reaction via UV irradiation. After UV curing, the present lenses stably maintained their shapes even in a water-swollen state and showed significantly improved mechanical properties compared to conventional lenses manufactured using a cross-linking agent. These lenses showed slightly lower water contact angles than the conventional lenses, although the water content was slightly reduced. The present photodimerization cross-linking method was found to be useful in reducing the tearability of soft lenses.