Quote -
If you're referring to SaintFox asking about how to get transparency between the sclera and the iris a page or two back and where the two met, that's because they were separated.
Separate UV islands, but not separate objects.

no, i don't think they were, according to bagginsbill.  they might have been on your eye.  but the posts went roughly, iirc:

• bagginsbill - hey, i have a cool new eye using the principles i was talking about.  the scelera, iris and pupil are all one material (and implied same UV).
• SaintFox - well, i'd rather use the other eye where i can have a soft edge to the iris because i have the geometry (i say geometry, because transparency needs some geometric consideration to work) and mapping to use transparency and soften the edges.
• bagginsbill - well, you can use shader magic to soften the edge of an iris.

my point is just that it's not a question of shader magic or anything else.  when it's contiguous, you can pretty much make the edges as soft was you want in the map itself.

edited to add- and maybe my perception is wrong, but that's how i read it.