Musannaf Ibn Abi Shayba 18:493

Abu Bakr narrated to us, he said: Jarir narrated to us, from Mughira, from Ibrahim, who said: If a slave’s ear or his eye is injured, then in it is half of his price. And if both his ears or both his eyes are injured, then in them is his entire price, or he [the master] hands him over to the one who injured him.