Identifying The Ideal Fluence For Extracorporeal Optimization Of Corneal Allogenic Intrastromal Ring Segments (Eco-Cairs)

Published 2025 - 43rd Congress of the ESCRS

Reference: PP02.08 | Type: Free paper | DOI: 10.82333/1kcn-b220

Authors: Antonio Cano Ortiz* ¹ , Timoteo Gonzalez Cruces ¹ , Álvaro Sánchez Ventosa ¹ , Marta Villalba Gonzalez ¹ , Elisa Palacin ¹ , José Carlos Díaz-Ramos Díaz-Ramos ¹ , María Dolores López Pérez López Pérez ¹ , Alberto Villarrubia ¹

¹Hospital Arruzafa,Cordoba,Spain

Purpose

Here, we compare the biomechanical stiffening effects of a novel ultra-high fluence corneal collagen cross-linking (CXL) protocol with conventional high-fluence CXL for extracorporeal corneal allogenic intrastromal ring segment optimization (ECO-CAIRS).

Setting

ELZA Institute, Zurich, Switzerland.

Methods

Eighty-four porcine corneas were divided into four groups: Group A (control), Group B (10 J/cm²), Group C (30 J/cm²), and Group D (60 J/cm²). Following epithelial debridement, Groups B, C, and D were treated with 0.1% hypo-osmolar riboflavin. UV-A irradiation (365 nm) was delivered at fluences of 10 J/cm² (18 mW/cm², 9:15 min) for Group B, 30 J/cm² (30 mW/cm², 16:40 min) for Group C, and 60 J/cm² (30 mW/cm², 33:18 min) for Group D. Corneal biomechanical properties were assessed via stress-strain extensiometry, focusing on the elastic modulus.

Results

Mean elastic modulus (5% strain) values were: Group A (1.39 ± 0.49 N/mm), Group B (1.83 ± 0.48 N/mm), Group C (2.25 ± 0.83 N/mm), and Group D (2.31 ± 0.88 N/mm). Ultra-high fluence groups (C and D) showed significantly greater stiffening than Group B (P = 0.041 and P = 0.015), with no significant difference between Groups C and D (P = 1.00). Group B exhibited significantly greater stiffening than Group A (P = 0.023).

Conclusions

Ultra-high fluence CXL enhances biomechanical stiffening compared to conventional high-fluence CXL, while in this extracorporeal context, endothelial safety is irrelevant.

We suggest cross-linking an allogenic corneal ring segment outside the body prior to insertion, because it may have several advantages: the increased stiffness and reduced immediate rehydration make the surgical insertion easier, and by killing all keratocytes with the UV-irradiation, the segment becomes sterile, preventing a) an inadvertent transfer of keratoconus keratocytes from a donor that potentially may have had undetected keratoconus, b) contamination with microorganisms and c) potential immune rejection.