b/o's with 1 swollen eye...help!

[flukenaround]

So I have 3 hens that I noticed today each have 1 eye starting to swell. I checked there eye real good for worms and didn't see any and there is no oozing or foul oder and they are all acting fine. I put a lot of work into my flock as we all do and don't want to loose them all now there gonna start to lay any day now. What can I do to treat this and has any one else had simlar problem/solution. Any info would be greatly appreciated.

Thanks