Hmm. I don't think it has to be both eyes for herpes. Not sure, but I could
swear people have had Herpes kitties have one bad eye. Is there a vet
opthamologist in your area? http://www.acvo.org/publicframe.htm

If I were you, I'd seriously look into a new vet.  Cortisone should work if
it's herpesvirus or conjuntivitis, and if it is prescribed, please follow
the directions carefully and use only the prescribed amount.  I used to use
it for my own eye allereges (which led to conjuntivits) and it burns like
hell.  You mentioned earlier the vet said Reggie had a cold, URI is
associated with herpesvirus in cat. But testing for the virus is not so
difficult, your vet should know how to do it.  Here's what I found on
testing, perhaps it will help your vet, but again I'd go to a new one.  I've
been there and done that with vets, I've spent too much time and money on
wasted tests, and felt my cats were becoming test subjects over the years,
til finally I said enough of this crap and searched high and low for the
best vet I could find, then had all their files moved over to the new vet
and we've been happy ever since.  Fortunately, I have 4 animals that see the
vet regularly and no vet wants to lose that clientelle, so it gives me a
little buying power when I say "no, this is what I've researched , now you
tell me why you want to do it your way, what are the benefits".

And as far I know herpevirus can just be in one eye, it does not necessarily
have to affect both.  The fact that the eye is not healing with the
antibiotics also supports herpesvirus.

Testing for herpesvirus

To diagnose a herpesvirus infection, after applying a topical anesthetic, a
scraping of cells is made from the eye and placed on a slide. The slide is
submitted to a laboratory for a specific test procedure known as an
Polimerase Chain Reaction (PCR) test. This test is quite specific when
compared to other tests. A different staining test can be performed which is
known as the Indirect Flourescent Antibody Test (IFA). While the IFA test is
not as precise as the PCR test, performing both tests simultaneously gives a
better infection indicator as to whether your cat does or doesn't have
herpes than either test alone.

I wish you the best of luck, please let us know how the test goes.

Is she pawing at it at all? When my eyes get itchy, I will scratch at
them with my finger, and then I make them worse. If I go to long, I
will get that inner lid kinda thing, which is even more annoying. I
just had to stop myself a few minutes ago. If I put a kleenex there
and hold it, I can get the itching to stop and not make my eye worse.

It could be that she has an allergy, or responded to an original
injury and made it worse.

Glad to hear you are near an opthamologist.

Did you talk to your vet about the herpesvirus test?  Btw, not to lay a
guilt trip or anything, but cat's hide pain extremely well, and they hide
illness as well.  Hopefully the new meds will work quickly.