Eye color: Is it a continuum?

[Hoihey]

I have always heard that eye color is based on dominant/resesive traits, with brown eyes being dominate. However, after looking at thousands of people in the eyes I don’t think this is the case. I’ve noticed that most eyes are not one color, they are a mixture of different colors
http://i64.tinypic.com/2cpuf06.jpg
http://i65.tinypic.com/1z1em1h.jpg
http://i68.tinypic.com/1zd582q.jpg
http://i65.tinypic.com/1zcifl5.jpg

As you can see, the color is not uniform across the entire eye, this can only be noticed in real life or in photos with pristine lighting. So what gives? Why are we taught in school that eye color is mendelian trait?

[Sp_loa]

Eye color isn't a simple case of recessive-dominant genes.
There are dozens of genes related to human iris pigmentation, and the combination of all of them is responsible for the exact shade of the color.
Every cell express different genes (genetic regulation) so even different melanocytes in the eyes of the same person can produce different amount of pigment (typically closer to the pupil there is more pigment).

[Imperator Biff]

Over 70% of eye colour variation is determined by a single locus, but no eye pigmentation is not simply a case of autosomal dominant vs recessive. It’s a polygenic trait, not Mendelian. Over a dozen genes are involved.