Are you sure you want to use the fresnel node? I never understood what it does (in poser 8). I would have *assumed* that it does something like refraction (and from your node setup you might have thought that, too), but it looks more like it rotates all normals by 90 degrees of the objects behind it (in the image left: a ball behind the fresnel node with ior 1). You could try the refract node instead, or, if you insist on using fresnel, explain what it does :-)

Just to add: Are your glasses double sided or single sided? That does make a difference with refraction and/or fresnel in particular.