On the moorland farm we would get a few sheep go blind every year, some years almost an entire batch. We were never completely certain which of the many possibilities it was, nor was the vet, and we were not convinced that antibiotic powders made any difference. We would give them antibiotics (in case it was listeria) and B Vits and they pretty much all always recovered. Any so blind they were in danger of hurting themselves we'd bring in and pen until they were safe. Mind, catching them wasn't as easy as you'd think - their hearing was not impaired! You would need two of you, and/or a dog or dogs, so that there would be sounds coming from several directions and you could confuse her and grab her.
The sheep's eye seems to be capable of extraordinary regeneration. I had one ewe got flystruck in her eye, she had collapsed in 300 acres of thick moorgrass and wasn't found for a few days, by which time I am afraid to say the entire eye had gone. We treated her, she recovered - and a year later she had a complete new eye, which looked perfect. She couldn't see out of it but you could only tell that because she didn't blink if you flicked your finger in front of it.