Well the link at the end is what I have found that best describes, to what degree it can,on what I have learned on eye colors and there coding. While semantically you are arguing the density of melanin, I am trying to say that you are specifically coded for your eye color, be it blue, green or polka dotted. Not saying that the color blue or the color green is created, but that your genes are saying produce x and x amount of melanin, which determines the color of your eyes.(BTW blood vessels behind the eyes are red, which is why albinos have red eyes because they have no melanin, while blue eyes do have some melanin but like the sky you only see blue)
http://www.athro.com/evo/gen/geframe.html
Oxygenated blood is red. De-oxygenated blood is blue. In earth’s atmosphere, you will never see de-oxygenated blood outside the body. As soon as blood is in contact with air, it oxygenates.