... seriously though, I've more or less seen that shade in the mirror before, when the hazel decided it wanted to be pale that day. Lime green actually happens. It just seems jarring 'cause it matches the hair :V
Probably also depends on the light shining on the eye as well. In Front Mission 4, a major character has eyes whose irises have
no color, causing them to reflect color light that's shining on them - his eyes were red over a video monitor at sunset.
Since the character in question was a Russian Zaftran spy who infiltrated the German army's officer academy, killing then stealing the identity of a cadet. The cadet did not have this condition, and one of your party members was an old friend of the original(and later, the spy), and (eventually) noticed this. Years later.
The fact that an officer would have a highly visible medical condition and not have it in his personnel file should be a red flag to something being wrong. Even more so is that it's a critical failure for planning - with the plan being made by a guy with an absolute hard-on for making plans - that a spy with such a highly visible condition was used to double as someone who does not - especially since this is exactly how he was found out. Well, that, and him blowing up half of his own army, and starting a war with another country and all.
Speaking of insane eyes from a Square-Enix game, doe Al-Bhed have vision problems with their swirly eys? Plus, is it right for a half-Al-Bhed to only end up with heterochromia(with proper, round irises/pupils)? I also don't recall seeing Braska up close enough to see his eyes, but I don't think they were blue.