Rene,
First of all, let me say great work.But I also have to say I'm not too familiar with this guy.
But from a sculptural and visual view I think the eyes are too small and need to be moved a little outward away from center.In other words;more centered in the eye socket based on the underlying skull.
Hope this helps and if I'm wrong;I'm sure someone on this fantastic site will correct us both..............Again..keep up the good work.........Wayne