I want to try and help you but need some more information to be able to.
What kind of tank is he in? Is there filtration, if so what kind? What are your readings for ammonia, nitrite, and nitrates? What is the temperature of the water? How often do you do water changes and how much?
How is his behavior? normal, less active, gasping.........???
Also can you describe a bit better what it looks like? All I have been able to find is eye fungus but the descriptions say it looks like a white cloud on the eyes.....is that what it looks like? I couldn't see real well in the pics, not enough to make a guess. As for the salt bath, I have never done one to any fish and really wouldn't know where to start, a little aquarium salt in the water is good for bettas though. If you can answer these questions, I'll do my best to try and figure it out for you.