I would rule out the BGK, they have incredibly large mouths, and arent capable of eating an eyeball so cleanly, i would suspect the GG.
When i had my BGK it did the same thing and nothing was allowed by its cave but all it does it nip a little bit around the back of the body. Im really doubting it being the BGK they are usually known for eating prey whole, not ripping out parts of bodies and especially as clean as it happened.