If you catch it early, say when there is just a small bit of white and it only started tearing, just a spray of LA200 will clear it up in a couple of days. If you wait longer and you have a lot of white, it will take at least a couple of weeks and it may appear to get worse before it gets better (This is with both a spray in the eye and a SQ/IM injection). The eye patches help but mine always seem to get it off after a day or two.
I treated a lot of cases this year from early to a bit late and they all cleared up. Even with the worst case they call still see just fine, although some of them looked pretty bad at the time.