Is this the caveling you are taking about? The one I found could help me with a human character I have that was mutated into form more adapted for life underground.There's a goblin mutation called caveling that gives them light blindness, a climb speed, and darkvision (not sure why that mutation specifies they get darkvision since goblins already have it). It's supposed to be the type of goblin that lives deep underground where there is no light.
Not sure if that's what you're going for. It's all I can think of at the moment.