Second-Generation Customized Corneal Cross-Linking (Elza-Pace) To Improve Vision In Patients With Keratoconus – Final Results With Up To 44 Months Of Follow-Up

PTK-assisted customized epi-on (PACE) corneal cross-linking (CXL) for keratoconus utilizes an epithelial map-guided phototherapeutic keratectomy (PTK) over the Gaussian elevation of the keratoconus. In contrast to previous customized CXL protocols, ELZA-PACE does not establish a single, but multiple gradients to achieve a customized treatment effect: the stroma beneath the PTK-treated paracentral epi-off region has greater oxygen availability and receives 20% more UV transmission. Second, riboflavin application creates a concentration gradient, with the highest levels localized over the PTK area. Additionally, a differential ultraviolet fluence gradient is applied, ensuring maximal energy delivery over the tip of the keratoconus.

ELZA Institute, Zurich, Zurich, Switzerland.

This prospective study involved ELZA-PACE (PTK-assisted customized epi-on CXL) being performed on 165 eyes with progressive keratoconus. We report on the topographic, tomographic, biomechanical, aberrometric, and visual outcomes. The procedure was performed by one of two surgeons (FH, ETN) at a single site (ELZA Institute, Zurich). All patients underwent a comprehensive assessment of corneal topography and tomography using, corneal biomechanics, ocular Aberrometry, and objective and subjective refraction before PACE, and at regular intervals post-surgery, with a follow-up between 12 and 44 months.

We will show how PACE successfully reduces corneal topographical asymmetry by up to 15 D and will detail the changes in topographic, tomographic, biomechanical, pachymetric, and aberrometric parameters reflecting corneal flattening and asymmetry reduction. Subgroup analyses will reveal demographic and pre-procedural corneal characteristics linked to significant flattening and regularization effects, alongside visual outcomes.

ELZA-PACE leads to marked reductions in corneal asymmetry in keratoconus, all without removing any stromal tissue. PACE improves the quality of vision by not only flattening the steep areas of the keratoconus but also by a coupling effect that regularizes the astigmatism in the upper cornea.