"The eyes are the windows of the soul - Children of the corn"
I've been researching about Magus' eye color why it changes from green to red & I came up with a conclusion. It seems that eye color have a connection to how strong the person's spiritual or magical potential. Commonly the eye color that have red, blue, gold & silver has strong spiritual or magical potential. Take DBZ for instance, when Goku changes to Super Saiyan its eye color changes from black to blue or gold(when he turns to Super Saiyan 4). Another fine example is Lunar Legend Tsukihime, its eye color signify demonic or anti-demonic powers. Another example is Naruto, Hyuga clan's eye color is gray(Byakugan) & Uchiya clan is red(Magenkyo eye). My observation in Chrono Trigger's Mystic eye color are blue, green & red... Magus' eye change from green to red probably because of his realization from his full magical potential. Its likely that anyone who has this color has a spiritual or magical potential.
Although my observation is circumstancial but in most cases, anyone who has those eye color has certain advantages compare to normal people.
DBZ should never be brought up anywhere.
Ever.
To each their own, I s'pose... *puts something in her signature just ta spite 'im* <3(*not really, but it sure works out like that, doesn't it?*)
Anyway, I'm not sure I can really think of any other examples of eye colors changin' that dun involve naughty stuffs or Dragon Ball Z, bu' yer more than welcome ta find and/or make s'more evidence that proves eye-color corrisponds ta magical prowess, babe. I'm not hones'ly sayin' it dun, but I ain' sayin' it does, either. I mean, let's look at some examples...
Ayla - Green eyes, no magic.
Crono - Green eyes, Sky magic.
Glenn - Golden/Blue* eyes, Water magic.
Lucca - Sky blue eyes, Fire magic.
Maou - Dull green, then blood red eyes, all magics(with Shadow affinity).
Marle - Green eyes, Water magic.(Ice sub-magic.)
Dalton - Black(...?) eye, Void and Copy magic.
Gran and Leon - Green-blue eyes, Sky magic.
Mayonnaise - Pink-grey eyes, Void magic.
Vinegar - Golden eyes, all magics.
Queen Zeal - Grey-green eyes, all magics.
Sara - Soft green eyes, unknown magic.(Assumed "all magics".)
Far as I can see, there's absolutely no constant in eyes or elements. It's all jus' kind'a random... Well, 'cept wid maybe th' Zeal family. They all seem ta have green eyes. Bu' still!