VEE 2023: Corneal cross-linking in the 21st century

Mitch Ibach, OD, FAAO, caught up with Optometry Times®' assistant managing editor, Emily Kaiser, to chat about his presentation, "Keratoconus and cross-linking in the 21st century," which he presented during the 2023 Vision Expo East meeting held in New York, New York.

Video transcript

Emily Kaiser:

Hi everyone. I'm Emily Kaiser with Optometry Times and I'm sitting down with Dr. Mitch Ibach, who presented "Keratoconus and cross-linking in the 21st century" at Vision Expo East 2023 in New York City. Welcome Dr. Ibach, thanks for being here.

Mitch Ibach, OD, FAAO:

Thanks, Emily. How are you?

Kaiser:

I'm good, how are you?

Ibach:

Good.

Kaiser:

Good, well, can you tell me a little bit more about your presentation?

Ibach:

Yeah, I had the opportunity to present a presentation, "Keratoconus and cross-linking in the 21st century," this past weekend at Vision Expo East in New York City and it was a jam-packed room. A lot of attendees came out to see this presentation.

We kind of talked about how keratoconus, not even in the last 100 years or century has changed a lot, but even in just the last 10 years. It's gone to better diagnostics, we have better optical devices, improved specialty and scleral contact lenses, and then we have an intervention to arrest disease progression in corneal cross-linking.

Kaiser:

Fantastic and can you share some tips for early detection of keratoconus?

Ibach:

Yeah, in my opinion, definitive diagnosis—kind of the earliest detection—happens around corneal topography. Corneal tomography and then epithelial mapping.

But the truth of the matter is about 35% of surveyed optometrist in the US have these technologies, and so I think of all of us as being detectives in keratoconus and trying to find the clues or the red flags that could tell us: the response needs to be to either get a corneal topography or tomography in our practice, or to refer that patient out for advanced diagnostic testing.

And so as I think through some of the big ones, for me, it's maybe a patient who has auto-refraction that's out of normal limits, they have 3 diopters or more of refractive astigmatism, they have auto-keratometry values that are 48 or 49. You know, that's almost always abnormal. It's the patient who has an abnormal retinoscopy reflex.

And then one that I think we overlook is just the otherwise healthy young patient who is not correctable to 20/20 in the phoropter. It just really warrants digging deeper and trying to figure out maybe what we're missing.

Kaiser:

Yeah. and how can clinicians start the treatment of keratoconus? Is there anything they can do in office?

Ibach:

I think first step is making the diagnosis and along step one, which is 1a for me, is to educate patients against mechanical eye rubbing. I think that's the number one modifiable risk factor in keratoconus. After we've made that education point for patients to stop rubbing their eyes and treat the underlying cause and maybe why they're rubbing, then I think the next step—if it's progressive keratoconus or refractive surgery ectasia—is corneal cross-linking.

Kaiser:

And can you tell me about some corneal cross-linking technologies that are under investigation?

Ibach:

Yeah, so currently, in the US, we have one FDA approved device for corneal cross-linking, that is epithelium-off corneal cross-linking. It uses riboflavin and ultraviolet light that causes a chemical reaction to kind of reweave or strengthen the fibers for a patient with keratoconus—or improving the biomechanical strength.

Really, you need 3 ingredients for cross-linking: you need riboflavin, that's your photochemical sensitizer; you need ultraviolet light; and then you need oxygen. Oxygen is the catalyst that continues to keep the reaction going. We're basically cleaving oxygen, and these fancy words called free-radicals, to make small little crosslinks—or chains, covalent bonds—in the corneal lamellae.

And so if I think of cross-linking being 3 things, right now we do epithelium-off, and there's a couple of reasons for that. Number one, the riboflavin penetrates better if you don't have the epithelium in place; number two, the ultraviolet light gets deeper in to the cornea, and the ultraviolet light is used up heavily by the epithelium; and then number three, oxygen is chewed up by the epithelium, as well, and so removing the epithelium removes some barriers to a sustained cross-linking reaction.

Some ways we can try to get around that is by pulsing the ultraviolet light—you can try to do more of a pulsed treatment rather than a continuous beam that's going to keep more oxygen around. You can use different loading sponges, different riboflavin concentrations, you can add surfactants to try to kind of loosen up the epithelium with the riboflavin, you can do different kinds of loading techniques, as well. And then finally, you can add oxygen. And so you can add oxygen with goggles—goggles that add oxygen around the front surface of the eye and the cornea—and this is what is being studied with hypoxia or oxygen boost goggles in Glaucos' phase 3 FDA clinical trial. Our practice is a part of that trial, and so I think the future is bright with maybe multiple technologies for epithelium-on corneal cross-linking.

Another form of cross-linking that's being studied is using drops—drops to try to induce cross-linking with lysyl oxidase changes compositions in the cornea. And so that's another option that may be coming.

Kaiser:

Interesting. Yeah, definitely sounds like a bright future. Totally agree. Is there anything else you'd like to cover that we haven't touched on?

Ibach:

Don't underestimate the amount of keratoconus patients you have in your practice. If you can find them first, you can really save irreversible vision loss for these patients. And I think it's, in my opinion, a two-step kind of treatment approach.

Number one, stop progression.

Number two, patients don't come to see us because they want to flatten their maximum keratometry value, they come to see us because they want to see better.

And so, while cross-linking is very effective, it is not a refractive surgery, so help patients so that they don't lose vision, but then also help them see better with optical or surgical devices in the keratoconic population.

Kaiser:

All right. Well, thank you so much for taking the time to talk today, Dr. Ibach, it's been a pleasure.

Ibach:
Awesome. Thanks for having me.