In my endoscopy I had in Feb 2011, I had the rings, and the biopsies confirmed. Up to 14 eosinophils per HPF. The GI immediately put me on a daily regimen of Pulmicort, and backed it off to once per week, four weeks later. The biopsies taken during my July 2011 endoscopy showed <5 eosinophils per HPF, and no rings.
After the TIF procedure in August, I started backing off the Pulmicort thinking that, since the eosinophils were a response to the reflux, and that the reflux is "now gone", the inhaler should no longer be necessary. I gradually got sicker and sicker, noticed a burning near the LES, started running a fever, lost my appetite, and had a general feeling of malaise. Had another endoscopy (and the pH study) in October, and the biopsies showed up to 14 eosinophils per HPF -- but no rings. Two doses later of Pulmicort over the course of the next week and I felt 10 times better -- and the heartburn-like pain has never reappeared.
So, in my case, I think it's pretty clear that the eosinophils are a response to reflux, and not food allergy. I'm not aware of any allergies, anyway. What's also clear is that in two separate biopsies, with two identical eosinophil counts, one had evidence of rings and the other one didn't. I think the rings would have reappeared if the condition had continued after October.
EoE isn't considered acute until you reach about 20 per HPF, but numbers greater than 10 are consistent with reflux, and can cause significant issues. You can't depend upon only a visual inspection to determine whether it's present or not -- it has to be a biopsy.
Yes, I have both the EoE and LPR...lucky me! ;-)