Femto-Cairs Biomechanical Evaluation Using High-Resolution Oct Elastography

This study aims to quantify the axial strain field after femtosecond laser-assisted corneal allogenic intrastromal ring segment (Femto-CAIRS) insertion on ex vivo porcine eyes. By utilizing a custom optical coherence elastography (OCE) technology, we investigated how the Femto-CAIRS procedure locally influences the biomechanics of the cornea.

The research was conducted in a controlled laboratory setting at the ELZA Institute, Zurich, Switzerland.

Porcine eyes were subjected to Femto-CAIRS, with ring segments being generated from ex vivo porcine corneas using the femtosecond laser (Ziemer Z8, Ziemer Ophthalmic Systems, Switzerland), and inserted into femtosecond-laser created stromal tunnels. The high-resolution OCT-elastography were used to quantify the axial strain profile after corneal allogenic intrastromal ring segment.

Structural imaging through optical coherence elastography tomography revealed the precise localization of the implant, correlating it with the surface contour of the cornea at the site of the ring implantation. In most cases, no significant differences were observed in the strain distribution images between the allogenic tissues and the recipient cornea.

For the first time, OCT-Elastography (OCE) was used to differentiate local strain profiles after Femto-CAIRS implantation. The mechanical behavior of the Femto-CAIRS implanted ring closely mirrors that of the cornea, and it does not seem to induce any unnatural stretching in the surrounding corneal tissue. Our preliminary results highlight a potential difference from our earlier published studies on PMMA rings, showing a distinct strain profile with Femto-CAIRS implants. Further research is needed to fully understand these variations, as they may have a significant impact on the nomograms for Femto-CAIRS, potentially optimizing implantation strategies and improving patient outcomes.