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Assessment of UVA-Riboflavin corneal cross-linking using small amplitude oscillatory shear measurements

Poster Details

First Author: I.Aslanides GREECE

Co Author(s):    C. Dessi   P. Georgoudis   G. Charalambidis   D. Vlassopoulos   A. Coutsolelos   T. Kitsopoulos

Abstract Details

Purpose:

The effect of UV-Riboflavin cross-linking (CXL) is usually measured by strip extensometry technique. Here, we propose a simple and reliable methodology for the assessment of the CXL treatment by utilizing an established rheological protocol based on small amplitude oscillatory shear (SAOS) measurements. It provides information on the average crosslink density and the elastic modulus of treated cornea samples.

Setting:

Private Ophthalmic Institution, State University and University Affiliated Research Institute

Methods:

Three fresh postmortem porcine corneas were used to study the feasibility of the technique, one serving as control and two receiving corneal collagen cross-linking treatment. Subsequently, five fresh postmortem porcine corneas received corneal collagen cross-linking treatment with riboflavin and UVA-irradiation (370 nm; irradiance of 3mW/cm2) for 30 minutes (Dresden protocol); the contralateral porcine corneas were used as control samples. After the treatment, the linear viscoelastic moduli of the corneal samples were measured using small amplitude oscillatory shear (SAOS) measurements and the average cross-linking densities extracted.

Results:

For all cases investigated, the dynamic moduli of the cross-linked corneas were higher compared to those of the corresponding control samples. The increase of the elastic modulus of the treated samples was between 122 and 1750 %. The difference was statistically significant for all tested samples (p=0.018, two tailed t-test).

Conclusions:

We are reporting a simple, accurate and reproducible method for quantifying the effects of cross-linking on porcine corneas treated with the Dresden protocol by means of small amplitude oscillatory shear (SAOS) measurements in the linear regime. The measured dynamic moduli, elastic and viscous modulus, represent the energy storage and energy dissipation, respectively, hence providing a means to assess the changing physical properties of the crosslinked collagen network after CXL treatment. FINANCIAL DISCLOUSRE: NONE

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