Yeah I know that dilemma well as two of my furbies came to me feral and have managed to tame down, even defleaing them and worming is traumatic for them although I can get oral wormers down them every 3 months.
Just so you know there is an antibiotic injection that lasts for 2 weeks found this out recently when Domino was given one when the vets thought he had a slight flare up of his FLUTD even though it turned out to be nerve damage due to him pulling his catheter out himself (think he wanted to come home, lol). Just thought I would let you know but would think they would prescribe looking at it cream for the eye to be administered.