A common problem with Genesis 8 characters is that the eyes tend to be too dark in Blender.
The reason for this is that the eye textures are quite dark.
Somehow Daz Studio manages to avoid this problem, but it is not so easy to emulate this in Blender. Therefore the Daz importer now has an option to brighten the eye textures. This option appears at the bottom of the import menu, and is set to a value which is reasonable for Genesis 8.
If Brighten Eyes is set to something else than 1.0, an extra multiply node is generated for the iris and sclera diffuse channels. It multiplies the eye texture with a more than white color, whose HSV value equals the Brighten Eyes factor.
And now the eyes render much better.
The eyes still look a little strange. It looks like the sclera rests like a disc on top of the eye, and is clearly distinguishable from the rest. But if you look carefully the same effect is visible already in the dark eyes on the top.