Study on mechanical and optical properties of poly(vinyl alcohol) hydrogel used as soft contact lens

Highly transparent hydrogel has been proposed as promising soft corneal contact lenses. In this paper, poly(vinyl alcohol) (PVA) hydrogels with high transparence were prepared by dissolving PVA powders into dimethyl sulfoxide (DMSO) aqueous solutions and followed by freeze–thaw cycle technology. The various influences such as PVA concentration, freeze–thaw cycle times and DMSO concentration on the tensile mechanical and transparent characteristics of the PVA hydrogel have been investigated. Results of the tensile mechanical investigation revealed that the tensile strength of PVA hydrogel increased with the rise of PVA concentration and freeze–thaw cycle times, but decreased with the increasing DMSO concentration. The results of optical tests indicated that the light transmittance of the PVA hydrogel increased with the increasing light wavelength, PVA and DMSO concentrations. Moreover, the light transmittance of the PVA hydrogel first increased and then decreased with the rise of freeze–thaw cycle times.