On the subject of dynamic UV re-mapping, please do not bother working out how to do that with the eyes. If you re-map the UV layout, then all the UV-based math in the shaders will break.

For example, I know precisely what the radius is on the cover, based on UV coordinates. I use this information in the shader to form the shadow ring, and the translucent ring, around the rim of the cover. I also use this information to know where the iris ends and the sclera begins, so that I have no specularity/reflection on the iris, but I do have specularity/reflaction on the sclera, and it transitions smoothly. You cannot remap the cover - it will totally change all the radius based math.

Instead, I use shader math to remap the UV coordinates for any texture map. Thusly, I can keep the same actual UV coordinates, while re-mapping other textures for this eye in the shader. For example, I can make a shader that uses iris images from V3 or V4 texture maps. Not a problem at all.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)