TouchOphthalmology interviewed Prof. Farhad Hafezi on why it’s taken until now to have an effective epi-on CXL solution.
Transcript:
Hi, this is Farhad Hafezi from the ELZA Institute in Zurich, Switzerland. I’m a corneal refractive surgeon and a cell biologist. The main reason why it has taken so long to have effective epi-on CXL is because back in early 2005/6, we hadn’t even identified all the factors that are needed for successful cross-linking to occur.
So nowadays we know that besides light and riboflavin, we also need oxygen, and this was only discovered in 2014 by my group in Geneva. And so once we knew that oxygen is a limiting factor, we knew that epi-on has two major limitations to overcome: we need enough riboflavin in the cornea, and we need enough oxygen at all moments. And personally, I always I was always striving for the most simple procedure possible.
So in terms of riboflavin transport into the cornea, we already had a solution using iontophoresis a few years ago, but this simply means yet another device. It’s not easy to put this little ring on suction ring onto the cornea. It falls off, the riboflavin goes everywhere. It just complicates things. So personally, we were looking to how to use penetration enhancers, the right concentration and composition to omit this additional technology just to use penetration enhancers and riboflavin.
That’s step one. The other step to developing an effective epi-on CXL solution was how do we overcome the limitation of oxygen transport into the cornea if there’s an intact epithelium? And one idea and we have done the basis in our scientific publications. one idea would be to not use the 21% we have around us in the surrounding air, but to have 100% oxygen around the conus. This is why two or three years ago, the concept of these oxygen goggles came up. That makes perfect sense, but again, yet another technology. So the quest in my eyes was to find the perfect combination of factors that allows us to do it epi-on without iontophoresis and without additional oxygen.
A big thank you to Cosima Mazzotta from Italy, because he published a few months ago three-year follow-up on his own procedure, where he did not need additional oxygen because he used a very clever combination of high frequency, pulsed light, gentle acceleration.
But he still needed iontophoresis. So the last year I’ve been working at the Swiss Federal Institute of Technology understanding how to bring more riboflavin into the corona without iontophoresis. We are there now. So what we have now is functioning epi-on at a high success rate without iontophoresis, with the ambient oxygen. And this is what we’ve all been looking for.
