So, after the initial review by the vet we took her back in the next day for a check up. The vet didn't think Arwen had sight in her right eye. It was still pretty swollen, red and there were no responses to the various tests. They recommended we go to a specialist and they managed to see her that day.
After the appointment the new vet was pretty worried and basically confirmed what our local vet was saying. She gave her some steroids and some eye drops and told us to come back in a few days to see if there was improvement.
Thankfully there was and she was getting a response to some of the tests. I'm due back again tomorrow to see if there is any further treatment.
You wouldn't notice anything was wrong with Arwen in her behaviour, she's been as energetic as ever.