Refraction Depth Bias in Unity - HELP

Hi everybody, I’m getting really mad!!!
I’m creating a shader for a shockwave material with refraction in Unity.

Everything is ok, and I managed to replicate exactly the Unreal one.

Except for the behaviour of refraction. Since refraction (at least in Unity/Amplify Shader) is made with Grab Screen Color, if a character is close, the same character gets refracted and distorted.

I checked in Unreal and through Depth Bias this happen just if the character is really close to the object.

There is a way to filter (adding depth bias) also in Unity?

After many research GPU Gems came to help, hope to try it tomorrow morning and see if I manage to solve it.