Blur effect throught glass What I'm trying to do in Blender is a blur effect in a way that, whenever something is not behind the crystal of the glasses, it should be blurred. That means, the sentence "Saw you there" should be clearly defined meanwhile "And I thought" should be blurred. Any ideas?

Thank you!
Set the lenses object pass index to a value of 1 

Then under the layers panel use the passes dropdown and enable Object Index



Render that out and then head over to the compositor. Create a node setup as illustrated by the image below: 

As you can see by this render, I believe it resolves your problem. 

Hope this helps.