When I bought my Oscar (start of September) she had one slightly damaged eye. She's been fine up until last week when it developed into popeye over night. It's only the damaged eye that is affected. I did a water change and then treated with Interpet No 9 Anti Internal Bacteria water treatment and added the required aquarium salt dosage. It's a 2 stage treatment, and I added the 2nd dose on (day 4) Sunday.

The eye hasn't got any worse but it doesn't appear to have gotten any better either. She's eating normally and seems to be behaving the same as usual.

I have read that the eye doesn't always return to normal. Should I give it more time or treat again (the blurb says I can start treatment again if required in 7 days time which would be this Sunday).

Yes of course, try treating again after a given time. However, is your water in good condition?

Yep water is fine. I have an API master kit.

From what I've read if it's in one eye then it's damage related, if both eyes then it's water quality. I guess as it couldn't see much out of it that perhaps it damaged it more on a stone or something.

It's not something I've ever have to deal with myself. If you water quality is good then I shouldn't worry too much about it being Popeye, I will also say that I don't see much point in using a bacterial medication if it is indeed just an injury, maybe something like melafix would be a better option? Maybe someone else will chime in with some advice.

popeye is usually being treated with pure salt or aquarium salt,
plus keeping the water pristine. however, popeye could be worse and
could make your oscar blind. (1 tablespoon/5 gal water)

I'm pretty sure it is blind in that eye already. I did use aquarium salt and have plenty more so I'll keep adding it with each water change.

Would increasing the frequency or amount of water changes help? I normally do 50% a week.

popeye is also caused by bad water condition.... unless your water is good,
salt will not matter all. moreover, adding salt should be based on the replaced
water after the initial dosage otherwise your fish will be damage with high
salt concentration. salt never evaporates, thus it remains in the tank when not
doing water change.

are you sure there is no more eyeball in it. or it is just blurred. blind oscar
looks like this. no left eye

Nothing seems to be working, if anything it's getting worse on a daily basis. I fear within the next few days that the eye will explode out of the socket all together. I've done lots of reading and there's a fair few reasons that popeye can occur in one eye. It's looking like some kind of gas build up and it seems there is no cure for that. It'll either get better on it's own or the eye will come out.

Assuming it comes out are there any treatments I need ready to go in to the water? or any other advice anyone can give me?

It doesn't seem to be suffering. It's still eating and acting normally which is a relief.

The eye itself is very cloudy and the reason I believe it to already be blind in that eye is because it can't see food that it swims past, if it turns around and sees it with it's other eye then it eats it straight away.

If another round of treatment fails to bring any relief halt all treatment and just ensure your water is in top condition and wait it out. I am sorry that you and your Oscar are dealing with this. I know how one can worry about such things. I hope the situation resolves quickly.