My Maya had an eye infection in Autumn. As soon as it was over in one eye, it started in the other one...
I kept putting ointment in her eyes, and cleaned her eyes as often as possible. After at least 5 weeks, it was over, and it hasn't come back since.
Be sure to keep your cats' eyes clean; use kleenex for that.
Success!

this is about Maya :
Maya looks with one eye now
Oh Maya, now it's the other eye!