Those are Awesome. Love the theme of the Army and beautiful paint job. Yes I agree those eyes are amazing. How did you do it?
I painted the eyes last, so as not to smudge them later. First I just painted the whole eyeball black. Second I painted a half-moon shape with Khorne red, and then a thinner line of Evil sun red over the upper part of that. Next I fixed errors with more black, shaping the red bit to look like an eye (cornea? the coloured bit of your eye?) and forming a shadow-line on the upper part of the eye. Then just add a white dot.
Basically it's simple, but in practise it's really fiddly, I have to hold my breath every time I touch the model with my brush, and I had to clean up mistakes with black and re-paint after nearly every stage, but it's worth it. Even I would not like to do this on every model.