Fresnel on shader, left eye, right eye...middle eye

Hello everyone !

I am having a little bit of an issue on my shaders :

I am using some Fresnel (on pretty much everything) but I noticed that the left eye and the right eye are not rendering the same effect.

It's absolutely logical and normal but it's a big issue as it create a disturbing effect.

I will be okay with a Fresnel averaging on both eye "the middle eye" but I have no idea if that is possible.

So that pose also a more general question of : can camera based effect be based on the "middle eye" ?

I look forward to your enlightenment, thanks.