The first picture is what I doodled in school. I love eyes, I draw them more than would be healthy, and I wanted to see if I can do it like this - inverted. It's not 100% perfect, but I'm quite satisfied with the result.
I'll definitely try to do more pictures like this, it makes me think about light and form in a whole new way.
Tool is just a black marker, I think 0,1 mm... some lines are too soft/nearly invisible in here, that's because of scanning. :c