How do you export eyes correctly?

SnowSultan

Can someone PLEASE explain how to export a Genesis 8 figure to Substance Painter with the eyes working properly? I absolutely cannot get the parts to accept their texture maps, even though the UVs come over correctly. I've tried hiding the Cornea, combining surfaces in Studio before exporting, and all kinds of other stuff and I also cannot find any specific instructions through Google. Help is appreciated, this is becoming frustrating.