HUGS
Piggies don't usually like having their eyes deal with; that is instinctive protective behaviour.
Yes, I have had it happen very occasionally; once just a few hours apart so I turned up at the vets with piggy with two bad eyes on the following day but in the other cases it happened while I was already treating and I caught it in the very early stages so it was not a big problem. It can happen when either the hay is particularly hard or when a piggy is focussing too much on the side with the reduced sight.
Please check whether your hay is too spiky and tamp it down with your hands if it is. I prefer soft meadow hay in my hay trays for burrowing and romping.
Are you additionally using artificial tear gel like visco tears or any other carbomer based tear gel? It is widely available online but a vet won't usually prescribe it because it is not a prescription-only medication. The extra hydration helps with the healing process especially in the deeper areas and does speed it somewhat in my own rather ample experience. It also helps with the overall comfort in the eye. You will need to wait at least half an hour after giving the antibiotic eye drops or gel to allow them to be fully absorbed first before you go in with the gel but it also eases the itchiness in the eye from the medicated drops.
Please be patient and persist. You will get past it all.