Abstract: Polymer-based portions comprise an index of refraction ranging from about 1.49 to about 1.55. In some embodiments, the polymer-based portion comprises the product of curing 45-75 wt % of a difunctional urethane-acrylate oligomer with 25-55 wt % of a difunctional cross-linking agent and optionally a reactive diluent. In some embodiments, the polymer-based portion comprises the product of curing 75-100 wt % of a reactive diluent and optionally one or more a difunctional urethane-acrylate oligomer and/or a difunctional cross-linking agent. Adhesives comprise an index of refraction ranging from about 1.49 to about 1.55. In some embodiments, the adhesive comprises the product of heating 10-35 wt % of a silane-hydride-terminated siloxane and 65-90 wt % of a vinyl-terminated siloxane. In some embodiments, the adhesive comprises the product of irradiating a thiol-containing siloxane and a photo-initiator with at least one wavelength of light that the photo-initiator is sensitive to.