Thank you again for all the comments guys!
@ linuxva: I didn't do anything special for the eyes, they were made the same way as the rest of the face
@ VFXdaily: no, I didn't use HD Geometry because my system cannot handle it...
So, this week I've spent another couple of days making one more image (I swear, this is the last one of this subject, this forum is starting to be too crowded of Walter White ).
Previously, I did the eyes in a simple way, just by projecting the photo on my model, but this time I made a proper eye-bulb, complete with Cornea, Iris and Sclera.
And for the fan of the show, I dresses him 100% Heisenberg!