The "one exposed machine eye" is more of a visual choice I make to show that a character is a cyborg or fully machine than anything truly "canon"--despite her limbs typically being left uncovered by artificial fur (leaving her mechanical arms and legs fully visible unless she covers them with clothing), she usually has both replica eyes in place at all times. I also used to do this fairly often with my art of Penny Possum, whether in her animatronic or cyborg form.