It doesn't have the specific verbiage that says you can see, like many of the other eye slot augmentations.
Good point. I defaulted when I first read it to assume you were replacing an eye with a weapon, thus it stops being an eye so no vision.
I think really it doesn't matter too much? The "lost eye" wound is a -2 to perception if a GM wanted to be dickish about it. Otherwise there isn't any penalty for only having one eye.
Still doesn't seem all that clear to me. Other eye augments go out of their way to say you can still see. This one doesn't.
So it's unclear at best.
raw is there any penalty for having only one eye?
AFAIK an augmentation doesn't interfere with the normal function of the limb unless it's explicitly stated. You can still talk in a normal tone of voice with Mighty Vocal Cords, perform a normal handshake with Clinging Hands etc.