sorry going to derail this thread a little bit but think it is worth it. Antibiotics in aquariums is an interesting thing. You can buy many antibiotics over the counter that are prescription for people, dogs, and cats. As a results antibiotics are terrible abused in our hobby and used in appropriately. People more often than not choose one and try it and if not working move on to the next. This essentially selects for antibiotic resistance. The amount of resistance in aquariums is scary. Even if you have never treated your fish ( the importer very well may have!)
Wailua is right is right in that we should be using the antibiotics as directed for the full course. This limits the chance of resistance but does not eliminate it.
Back to they eye. There several possible causes for pop eye and bacterial infections can be one of them.