Polysiloxanylalkyl methacrylates, such as methacryloxypropyl tris(trimethylsiloxy)silane (TRIS), have been used extensively in rigid gas-permeable contact lens materials due to their ability to produce high oxygen permeability in the resulting polymeric material. In this study, the role of TRIS was evaluated as a component in silicone hydrogel materials based on polysiloxane-based prepolymers. It was found that it not only gave high oxygen permeability, but also gave hydrogels with better tear strength and lower modulus. These changes in properties are all favorable for applications such as oxygen-permeable hydrogel lenses.