Posters

Flap and residual stroma biomechanical properties following high-irradiance CXL combined with myopic LASIK: an ex-vivo study

Poster Details

First Author: G.Asimellis GREECE

Co Author(s):    A. Kanellopoulos                    

Abstract Details

Purpose:

To evaluate ex vivo biomechanical and enzymatic digestion resistance differences between standard myopic LASIK compared to LASIK+CXL, in which high-irradiance cross-linking (CXL) is added.

Setting:

LaserVision.gr Clinical and Research Eye Institute, Greece

Methods:

Eight human donor corneas were subjected to femtosecond-assisted myopic LASIK. Group-A (n=4) served as a control group (no CXL). The corneas in LASIK+CXL group-B were subjected to concurrent prophylactic high-irradiance CXL (n=4). Saline-diluted (0.10%) riboflavin was instilled on the stroma, subsequently irradiated with UV-A through the repositioned flap. The cornea stroma and flap specimens were separately subjected to transverse biaxial resistance measurements; biomechanical differences were assessed via stress and Young’s shear modulus. Subsequently, the specimens were subjected to enzymatic digestion resistance tests (Collagenase digestion).

Results:

For the corneal stroma specimen, stress at the 10% strain was 128±11 kPa for the control group-A versus 293±20 kPa for the LASIK+CXL group-B (relative difference Δ=+129%, p<0.05). The stress in group-B was also increased at the 20% strain by +68% (p<0.05). Shear modulus in group-B was increased at the 10% strain by +79%, and at the 20% strain by +48% (both statistically significant, p<0.05). The enzymatic degradation time to dissolution was in group-A 157.5±15.0 minutes (min) versus 186.25±7.5 min in group-B (Δ=+18%, p=0.014). For the flaps, both biomechanical, as well as enzymatic degradation tests showed no significant differences.

Conclusions:

LASIK+CXL appears to provide significant increase in underlying corneal stromal rigidity, up to +130%. Additionally, there is significant relevant enzymatic digestion resistance confirmatory to the above. LASIK flaps appear unaffected biomechanically by the LASIK+CXL procedure, suggesting effective CXL just under the flap.

Financial Disclosure:

One or more of the authors travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented