Did they happen to see if possibly the feeder animal bit your balls eye? This is a risk feeders biting as
They are fighting for their lives essentially. It's a risk that we take when we feed live. If this did happen feeder bites can lead to infection, as well as an injury like this could result in blindness. Take him to the vet to get his eye looked at. In future feedings feed frozen thawed or fresh killed. If your ball is picky and you absolutely have to feed live you could stun the feeder or you will have to watch extremely carefully.