Hi Dianne,
I didn’t know what this was, and had to Google.
I’ve never been diagnosed with it. However, I’ve had repeated bouts of eye inflammation (always the same eye) that resemble conjunctivitis.
Despite appearances, these weren’t bacterial conjunctivitis (swabs from my eye actually showed fewer bacteria than is usual for most people - therefore not an infection).
An extremely rude, chauvinistic and misogynistic consultant at the eye hospital was more-or-less convinced it was a rare complication of chlamydia, and presribed antibiotics for that, even before the results came back.
As I’d not been sexually active for some years, I was sceptical, but had no idea how long it might lie dormant, so went along with this. Surprise, surprise, the antibiotics didn’t help, and the test showed I DIDN’T have chlamydia.
The horrible consultant nevertheless pronounced that I was much better, and therefore that the antibiotics had worked, even though I didn’t have the condition he’d prescribed them for. 
It’s episodic anyway, so personally, I think any improvement was coincidental, and nothing to do with the antibiotics. In fact, I don’t agree that it HAD improved, when he saw me the second time, but he seemed to have a vested interest in recording that his treatment was right, and that I’d responded.
Needless to say, I’ve never gone back, but just endure the regular flare-ups now.
It’s never been officially diagnosed as anything. The best my doctor has been able to come up with is that it’s some kind of allergy, but I’ve never heard of anyone being allergic in only one eye before!
When I Googled keratitis, I noticed that the images and descriptions of symptoms look very similar, and also that it responds to steroid eye-drops - which are the only thing I’ve ever had that helped (almost instantly!)
However, you can’t go on them long-term, as it’s associated with risk of cataracts and glaucoma, among other things - I expect you already know all this, if you’ve been treated for keratitis.
Like you, I’ve wondered if the episodes could be linked to my MS. Even before my diagnosis, I wondered if the repeated eye inflammation was a sign of “something serious”.
When the truth emerged that I had MS, I naturally assumed it was all connected somehow. But medical opinion still seems to be “No”.
I’m still getting fobbed off with: “allergy”.
Tina