ARVO 2025: Stromal keratitis in the ZED study

Video Transcript:

Editor's note: The below transcript has been lightly edited for clarity.

Christina Prescott, MD:

Hello. I'm Christina Prescott from NYU Langone. I'm at NYU Langone, I'm the director of the cornea service. I'm the Vice Chair for education and the residency program director. And I'm here at ARVO in Salt Lake City, and today I'm presenting on stromal keratitis in the ZED study.

I think pretty much everyone here knows about the ZED study, that is the double-blind randomized control study looking at long-term suppressive use of Valtrex (valacyclovir) for herpes zoster ophthalmicus. As those of you know that study looked at all outcomes of recurrence of zoster in patients with a history of herpes zoster. So my specific project that I'm presenting today is looking at stromal keratitis and the rate of recurrence of stromal keratitis in this population, both in the placebo and in the treatment group. One thing that was really interesting is something we didn't really know what presentation would be the most common, but stromal keratitis was actually by far the most common occurrence in the ZED study.

So almost 20% of the participants in the ZED study actually developed stromal keratitis at some point during the study. There was no significant difference between participants who were on the placebo versus the treatment arm, but it was notable that this was almost 20 percent of participants did, at some point, get a diagnosis of stromal keratitis occurring during the study. So interestingly, most of these recurrences actually occurred at scheduled study visits. So these weren't typically events that cause participants to come in for an acute visit. These were events that were incidentally noted by the treating investigator during their study. What this means is most of them were relatively asymptomatic in terms of sometimes participants didn't even present with any symptoms. It was just that the investigator during their careful examination noticed that there was a recurrence or development of stromal keratitis. So the good thing about that is that most of these were relatively mild.

The vision in the participants actually remained excellent even with the occurrence of stromal keratitis. That's something that's reassured. Most of these participants did not lose more than a line of vision, even with this episode. Of the participants who developed these episodes, most did have a history of stromal keratitis in the past, most were on, at some point, had been on steroids for treatment in the past, either a stronger steroid or a lower potency steroid. Interestingly, there wasn't a difference among participants who are on a stronger steroid versus a lower potency steroid.

And I think one of the really important findings of this sub-analysis is that a low-potency steroid probably is both effective and safe for patients, participants with stromal keratitis. So we don't necessarily need to treat these participants with higher-potency steroid most of the time, keeping on a low-potency steroid and increasing the frequency of the low-potency steroid versus switching to a stronger steroid is effective in treating the stromal keratitis. I think the big take home from my study is that stromal keratitis is very common, more common than we'd realize. It was not significantly different on participants on the treatment arm versus the placebo arm, but low-potency steroids was effective in reducing the occurrence of this and is likely effective in treating it with just an increase in the frequency, rather than actually having to switch to a stronger potency steroid. And reassuringly, most of these participants did keep good vision throughout.

So that's, I think, also very reassuring. So it's interesting that I think that what this really tells us is that stromal keratitis is probably a much more common finding than we realize, because most of these events, as I mentioned, were actually found during the scheduled study visit. So these weren't necessarily events that brought participants in. So I think it tells us that we're we need to really be looking for stromal keratitis, and that that's something that's more common than we realize. But reassuringly, it tells us that most of these participants still do very well. I think this should tell us that, you know, if you do have a patient with stromal keratitis, that I think the first one is really treating them with a lower-potency steroid and then maybe increasing the frequency, rather than going right to a higher-potency steroid, which may not be necessary for most of these patients.