AAO 2024: New study shows promise for MICE procedure in treating corneal neovascularization

This transcript has been lightly edited for clarity.

Kamran Riaz, MD: Hello everyone. My name is Kamran Riaz, and I am a clinical professor of ophthalmology at the Dean McGee Eye Institute at the University of Oklahoma in Oklahoma City. Today, I'm very excited to talk about a research project that we presented, actually one of our medical students presented concerning mitomycin intravascular chemoembolization for treating corneal neovascularization, aka MICE, because that's a big mouthful.

And, so basically, what does this procedure involve? We know that corneal neovascularization, there are many treatments that are out there, and they can be very difficult to treat with injections such as anti-VEGF, laser therapy, diathermy. And so, a couple of years ago, an ophthalmologist out of North Carolina by the name of Dean Ouano came up with this idea that what if we injected mitomycin seed directly into some of these feeder vessels, and as a result, we could permanently and irreversibly eradicate corneal neovascularization and prevent longer or more intensive procedures and, or, you know, obviate the need for surgical interventions such as penetrating keratoplasty.

So we had, previously had seen case reports and smaller publications. And so what we presented today was a series from 15 surgeons across the world of 107 eyes with 1 year follow up after having done MICE as a primary or a precursor therapy. And what we found across the board, from from the the international cohort, is that MICE works and was able to maintain regression in about 70% of patients at approximately 3 to 6 months. Some patients did need repeat treatment, but those that needed repeat treatment did well with 2 or 3 treatments. But other patients that ultimately need surgical intervention, but by decreasing the unwanted neurovascularization, these patients were able to have successful corneal transplantation without needing or having graft failure or other complications that can happen from doing penetrating keratoplasty in highly neovascularized, neovascularized eyes. So, basically, this is a procedure I think that offers a lot of promise. It offers a different tool in the toolbox for a condition that can be very challenging. And so while the data now is still very early, with 1-year data and long-term followup outcomes, I think it's very promising, and I would encourage corneal surgeons to consider this and hopefully contribute some cases for us going forward, so we can have more long-term followup from across the globe.

So, short-term outcomes with this procedure are very good. I think what we're learning is that patient selection is key. Ideally, we want to find neovascularization with 1 or 2 of what we kind of define as these juicy, beefy, fat vessels that are amenable to canulization. If we find wispy, kind of these wimpy, kind of panacy-like vessels, those don't respond well, and they're very difficult to cannulate. And we've had, you know, we've heard of anecdotal reports of surgeons injecting into the stroma, which we certainly do not advise, because that can be damaging to the corneal endothelium and the ocular surface. So, short-term, what we're learning is that if we find the right patient, they can typically do well with a single therapy session. Some patients do need repeat therapy. And what we're finding is that there are some patients that are not good candidates. For example, patients with neurotrophic disease are not good candidates. And we had one complication from the surgeon, contributing surgeon, where that patient ultimately lost the eye, but that was a highly neurotrophic cornea, and unfortunately, the patient was also abusing topical anesthetics. So again, we are still in the early pioneering days of this, and once we find out who's the best patient for this, I think the long term outcomes will also be good, but that certainly remains to be seen, but it looks very promising at this time.

Well, as with any surgical procedure, you're worried about things like infection bleeding, need for repeat therapy. Thankfully, in our case series, we saw no cases of infection. We didn't mention about 25% of patients did need repeat therapy. So to me, right now, that's probably the biggest complication, so to speak, is that some patients will need multiple sessions. So proper patient counseling, proper patient education is going to be key. I did mention one of the long-term or I guess the more devastating complications we did lose one eye to the evisceration. So again, I think finding the right patient is going to be very important, and realize that this is not a one-size-fits-all type of a procedure for all types of corneal neurovascularization, but rather it works for kind of very specific types of corneal neurovascularization, for example, especially due to herpetic disease or perhaps graft rejection. These are the ones that probably work the best that you want to see fat, juicy vessel. Is, along with lipid keratopathy associated with that, those are the types of eyes that will do the best.

Yeah, as far as comparison with what's on the market and what we've been doing for years, we've not done any head-to-head studies and comparison to some of those treatments. But we know that, for example, it works better than anti-VEGF. A lot of times with corneal neovascularization, the new vessels are going to be wrapped in a blood vessel known as parasites, or a blood cell known as parasites, which basically decreases the effectivity of anti-VEGF in those particular types of eyes. Comparing, we know that needle diathermy cautery certainly can work, but may often need multiple treatments and can be quite painful. I don't, I'm not suggesting that mice should replace all of those, but certainly I think gives surgeons with a different tool to use in their respective patient populations.