BIOMECHANICAL STIFFENING EFFECT IN ULTRA-HIGH-FLUENCE EXTRACORPOREAL CROSS-LINKED CORNEAL ALLOGENIC INTRASTROMAL RING SEGMENTS (ECO-CAIRS)
Published 2026 - 30th ESCRS Winter Meeting
Reference: FP05.11 | Type: Free Paper | DOI: 10.82333/611f-xt19
Authors: Farhad Hafezi** 1 , M. Enes Aydemir 1 , Léonard Kollros 1 , Mark Hillen 1 , Keith M. Meek 2 , Craig Boote 2 , Sally Hayes 2 , Shady T. Awwad 3 , Michalina Depczyńska 1 , Nikki Hafezi 1 , Emilio A. Torres-Netto 1
1ELZA Institute,Zurich,Switzerland, 2School of Optometry and Vision Sciences,Cardiff University,Cardiff,United Kingdom, 3American University of Beirut Medical Center,Beiruit,Lebanon
Purpose
To evaluate the biomechanical stiffening effect of ultra-high-fluence corneal cross-linking (CXL) compared with conventional high-fluence CXL for optimizing corneal allogenic intrastromal ring segments (ECO-CAIRS) before implantation.
Setting
ELZA Institute, Zurich, Switzerland.
Methods
Eighty-four freshly enucleated porcine corneas were randomized into four groups: control (no CXL), 10 J/cm², 30 J/cm², and 60 J/cm². After epithelial removal and riboflavin saturation (0.1% hypo-osmolar Ribo-Ker), ultraviolet-A irradiation (365 nm) was applied using the C-eye device (EMAGine AG, Zug, Switzerland). Fluences were delivered at 18 mW/cm² for 9′ 15″ (10 J/cm²), 30 mW/cm² for 16′ 40″ (30 J/cm²), and 30 mW/cm² for 33′ 18″ (60 J/cm²). Biomechanical properties were assessed ex vivo by stress–strain extensiometry, and elastic modulus values were calculated at 5% strain.
Results
Mean (±SD) elastic modulus values were 1.39 ± 0.49 N/mm (control), 1.83 ± 0.48 N/mm (10 J/cm²), 2.25 ± 0.83 N/mm (30 J/cm²), and 2.31 ± 0.88 N/mm (60 J/cm²). Ultra-high-fluence groups (30 J/cm² and 60 J/cm²) showed significantly greater stiffening than the 10 J/cm² group (P=0.041 and P=0.015, respectively), with no difference between 30 J/cm² and 60 J/cm² (P=1.00). The 10 J/cm² group was significantly stiffer than controls (P=0.023).
Conclusion
Ultra-high-fluence CXL (≥30 J/cm²) produces superior biomechanical stiffening of corneal tissue compared with conventional protocols. When applied extracorporeally for ECO-CAIRS, this approach eliminates endothelial safety concerns and facilitates surgical handling by creating rigid, acellular segments that simplify insertion and reduce corneal swelling. These findings support the use of ultra-high-fluence CXL for biomechanical optimization of allogenic ring segments in keratoconus rehabilitation.