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@ MikeJ,

Your image clearly shows (as did one of bagginsbill's) that refraction can counter concavity. In fact I think there is too much refraction in the "Convex-with refraction" image, and that a real iris does not appear so close to the cornea. However I am still not convinced that there is any good reason to use a concave iris, when a real one is convex. I will stand to be corrected on this point, but I have not seen any convincing evidence so far. Cobaltdream posted some links to good photos of eyes, and seems to think they display deviance of a concave appearance. I look at those same photos and see nothing but evidence of a shape that is roughly a convex toroid.

I think that a toroid that's set back from the sclera by an appropriate amount would probably produce a more accurate image. If I interpret MikeJ's wireframes correctly, his iris isn't set back from the sclera, and there's no dent in the middle for the pupil, either.

-- I'm not mad at you, just Westphalian.