I've had pink-eye in my flock, round and round, all summer.
The vets told me that jagging them with Tetroxy LA was as effective as eye ointment. They also said it's been a serious year for it round here.
In some cases I've jagged three times, 3 days apart each AND used Orbenin ointment in their eyes.
One or two, on their second or third time with it, did heal on their own - I presume they'd become a bit immune. On the other hand I've had sheep blind for days and worried I wasn't going to cure one (I did in the end).
I kept the worst affected wether in a pen for a fortnight, so I could get to him and treat him easily for the time it took.