Enhancing Corneal Allogenic Intrastromal Ring Segments Using Ultra-High-Fluence Corneal Cross-Linking (Eco-Cairs)

Published 2026 - 44th Congress of the ESCRS

Reference: FP30.07 | Type: Free paper | DOI: 10.82333/bq5a-yq10

Authors: Prof. Dr Farhad Hafezi** ¹ , Dr Mark Hillen ¹ , A/Prof. Shady Awwad ² , Mr Léonard Kollros ¹ , Mrs Nikki Hafezi ¹ , Dr Emilio A. Torres-Netto ¹

¹ELZA Institute,Zurich,Switzerland, ²American University of Beirut,Beirut,Lebanon

Purpose

To introduce a novel surgical modification designed to improve clinical predictability and long-term outcomes of femtosecond laser–shaped corneal allogenic intrastromal ring segments (CAIRS). By applying extracorporeal ultra–high-fluence corneal cross-linking prior to stromal implantation, the technique aims to enhance biomechanical stability, increase resistance to rehydration and enzymatic degradation, and reduce the risk of postoperative complications, thereby improving structural integrity and refractive stability (ECO-CAIRS).

Setting

Single-center retrospective analysis at the ELZA Institute, Zurich, Switzerland

Methods

20 eyes of 20 patients with stable keratoconus (maximum K 58.00–69.80 D) and corneal thickness ≥400 µm at 5 mm from the pupil center were included. Corneal allogenic intrastromal ring segments (CAIRS) were prepared from donor corneas using a femtosecond laser. Segments underwent extracorporeal ultra–high-fluence cross-linking (30 or 60 J/cm² UV) prior to implantation and were inserted without air-drying or prolonged dehydration.

Results

Insertion was uneventful in all cases. Ultra–high-fluence cross-linked CAIRS maintained marked stiffness throughout implantation, without intraoperative softening. Segment thickness decreased by approximately 50% immediately after high-fluence CXL compared to baseline, with partial re-expansion observed within days following stromal insertion.

Extracorporeal ultra–high-fluence CXL increases CAIRS stiffness and structural stability, improving implantation dynamics and potentially strengthening refractive impact.

Conclusions

This modification offers clear surgical and biomechanical advantages over unmodified or air-dried CAIRS. Increased segment stiffness improves intraoperative control and reduces re-swelling during implantation. Ultra–high-fluence UV treatment renders the segment acellular, creating a stable collagen scaffold. The transient thickness reduction allows implantation of larger-volume segments, potentially enhancing the topographic effect. Further clinical studies are needed to define the relative contributions of segment volume and intrinsic stiffness to refractive and biomechanical outcomes.