Has anyone tried using P3D Charlotte G3F character? Her eyes are broken. The creator made the default iris size 25% larger. Which looks really good. However, it causes a distinct black ring inside of her iris that can only be fixed by forcing the iris size back to 0%. Doing that changes her appearance quite a bit. The black ring cannot be fixed with the G3F "Eyes iris correction". Because that moves the entire iris in or out. The ring does not occur on the outside of the iris. It occurs right in the middle. Like the act of increasing the iris size broke the texture. Anyone seen this or have any ideas?
I suspect the PA enlarged the iris diffuse map but maybe not the alpha map so they might not be coinciding. Or the fact that the G3 eye is essentially a buldged sphere and the geometry is not playing nicely with the bigger iris when rendered. Or it could be a hundred other things. Is the problem apparent when rendered or non or both?
Some people actually have that dark ring around the iris - it's called a limbal ring. If you don't like it but want to keep the larger size, try a different set of eye textures from a different character, or edit it out yourself.
What you're seeing when you set the iris size to normal is the edge of sclera covering up the outside of the iris - I suspect you're also getting a really sharp transition between the sclera and iris?