What happened to vocaloid oliver's eye?

He was abused.

Or i guess the second reason was he was a slave in Britain and he tried to escape and he got his eye shot or something.

But the best answer would be he was abused by his parents.

Ansewr 2:

Since OLIVER was made by PowerFX (and VOCATONE), PowerFX VOCALOIDs are based off monsters. For example, Sweet ANN is based off " The Bride of Frankenstine", and Big AL is based off "Frankenstine". Sweet ANN and Big AL have stiches in some parts of their body. But, according to Vocatone the reason he has bandages instead of stitches was because stitches did not suit him.