When I was in an undergrad Psychology class in college, we had to volunteer to help one of the teachers/grad students with their experiments for class credit, and one that I actually worked on was this:
http://psychology.uga.edu/people/bios/faculty/JBrownDoc/Brown.1993.pdf
It was a study that looked at a person's perception of certain illusions made with alternating black and white shapes and blinking lights (real trippy), and found that those with darker eye pigments didn't see the illusion as often as those with lighter pigmentation. It roughly corresponded to skin color, but not necessarily.
I was the melanin measurer. I had one of those eye microscopes that they use when you get tested for contacts, and I had to figure out what level of pigmentation any given cornea had.
So I'm getting credit for gazing into some lovely co-eds' eyes and flirting with them. Oddly enough, telling girls that they have pretty eyes doesn't work so well from the other side of a microscope.