I had something similar looking with my emperor angel but he was in my DT so I couldn't treat with any meds. I think he had scraped it on a rock or something and it got bigger and you could see the outside layer was getting cloudy and milky and after a about a week, the outer skin layer of the eye looked like it was peeling and when it was completely off, it was all good.
for the antibiotic treatment to be effective you need to stick with the same treatment for a min 7-10 day course.
I think the best would be a kanaplex, furan2 and metroplex cocktail. This will give you a broad treatment when dealing with an infection. provide plenty of air exchange. Kepp the water quality good as well.
Also a Acriflavine bath might be helpful.
You will need to so a second (maybe even a third) prazipro treatment 5-7 after the first one but not sure if it can be done at the same time as the antibiotics.
