An article by Prof. Farhad Hafezi, MD, PhD, FARVO, Medical Director of the ELZA Institute, published in the November/December issue of Cataract and Refractive Surgery Today, details the latest advancements in corneal collagen cross-linking (CXL) research. Switzerland, and specifically Zurich, have been at the forefront of CXL innovation for over two decades. For the last 20 years, most surgeons have performed the epithelium-off (epi-off) CXL procedure using the Dresden protocol (which requires UV irradiation at an intensity of 3 mW/cm² for 30 minutes) or an accelerated cross-linking protocol (9 mW/cm² for 10 minutes). Accelerating the procedure is convenient for both doctor and patient, but the problem is that the more the procedure is accelerated, the lower the eventual strengthening effect is on the cornea. However, Prof. Hafezi and his team have developed a new epi-off CXL protocol that delivers similar corneal strengthening effects as the Dresden protocol but in a shorter duration.
The team performed UV irradiation at an intensity of 18 mW/cm² for 9 minutes and 15 seconds, which delivers a UV fluence of 10 J/cm² compared to the traditional 5.4 J/cm² used in the Dresden protocol and almost all previously used accelerated protocols. The laboratory results of this new protocol indicate that it is effective in providing corneal stiffening effects that are comparable to the Dresden protocol, without the need for any further modifications to the CXL procedure than UV irradiation settings.
In addition, the team has also developed an epithelium-on CXL protocol that uses a riboflavin solution with penetration enhancers, instead of the need for supplemental oxygen or iontophoresis. The laboratory results of this new protocol show similar corneal stiffening effects as epi-off CXL using an accelerated protocol of 9 mW/cm² for 10 minutes. One of the key advantages of this new protocol is that it avoids the potential drawbacks associated with removing and regrowing the epithelium.
Furthermore, Prof. Hafezi’s team is also investigating new methods to improve the treatment options for keratoconus and infectious keratitis. They have access to cutting-edge corneal biomechanical assessment instruments, such as the high-speed air puff corneal deformation device, the CorVis ST and the Brillouin Optical Scanner System, which have the potential to provide new insights into keratoconus. Additionally, the team is working to enhance the photoactivated chromophore for keratitis-CXL (PACK-CXL) technique for infectious keratitis treatment and have already established that higher fluences than the Dresden protocol’s 5.4 J/cm² may be required to successfully treat many cases of infectious keratitis.
To conclude, the article highlighted several promising advancements in CXL research by Prof. Farhad Hafezi and his team at the ELZA Institute in Switzerland and the University of Zurich’s Center for Applied Biotechnology and Molecular Medicine (CABMM). Their work on epi-on CXL, the new epi-off CXL protocol and PACK-CXL hold much promise for the future.
