Do you mean eye 'pigment' color or eye 'shine' color?
I've read that red eye 'shine' is related to cotton coat 'texture' where other eye 'shine' colors are related to silky (blue, green, gold) and possibly 'modified' (orange) coat textures...not sure you can trust my word or memory on that, though...lol
Brody and Mia have blue/green and green/gold most of the time when I've noticed, in varying shades for eye 'shine' colors depending on light and angle, and both have silky coats. Eye 'pigment' color is dark for both, as is the Yorkie standard.
Eye 'pigment' color is protein related, as is coat color, as I understand it...but there are additional factors, too, such as hair follicle/shaft structures, light reflectance, etc. I am interested in these things, but not an expert for sure.
I think there is a 'sticky' about coat color...very interesting.