This summer, however, we just can't keep on top of it. Our most recent bout meant a vet call; he got his tear ducts flushed, went on oral antihistamines, got steroid ointment in both eyes, and had an initial dose of banamine to get the swelling down.
About 10 days after that vet visit, his left eye started getting goopy and a little swollen again. Back on the oral antihistamines he went, and we started up regular flushing with saline solution. That was last Tuesday. Then he ran out of the oral antihistamines and the vet is having some trouble getting him more, so he went on a lower-powered one that the barn had around as a stop-gap.
Here's about what it looks like right now; photo taken on Thursday after flushing.
He's now wearing his fly mask 24/7, and has been switched back to the last few bales of the old hay. He actually seems to be making some progress on that regimen. The swelling is down slightly, as is the discharge. We've actually eased off on the regular saline flushes, which is happier for all concerned as he is a jackass about them. (I can't really blame him, honestly.) I'm examining the eye closely on a regular basis and the red irritation is easing. There's never been the slightest sign of cloudiness or any problems with the eye itself, both per the vet and my own continued monitoring.
The only thing I can think is that the Cushing's is depressing his immune system and leaving him more susceptible to eye problems. Probably he gets them slightly irritated from his normal allergies, and then rubs and rubs to itch them, and then escalates the problem. Hopefully as he settles in with the medication his own body will start to fight back a little better.