Board Thread:Metal Gear Solid V/@comment-25277765-20140831060343/@comment-1504072-20140831101122

Solid Snake has blue eyes in MG1, MG2, MGS4. I only think they were "green" in MGS2, but I'm not sure. Eye color also changes appearance with lighting conditions, so that's something to consider. It's possible Big Boss's single eye in MGS4 is not his own, given that his body was rebuilt (maybe not Solidus's or Liquid's, but that's speculation). Another consideration is that they gave a lighter eye color to young Big Boss because he was a "good guy", and made them darker as he became a "bad guy," from a character design perspective (I think I read something about this somewhere, but can't recall exactly where at the moment).