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Cornea and Ocular Surface

Analysis of Biomechanical Response After Corneal Crosslinking with Different Fluence Levels in Porcine Corneas

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Pages 719-723 | Received 01 Mar 2022, Accepted 14 Apr 2023, Published online: 05 May 2023
 

Abstract

Purpose

To evaluate corneal stiffening of porcine corneas induced by corneal crosslinking (CXL) with constant irradiance as a function of total fluence.

Methods

Ninety corneas from freshly enucleated porcine eyes were divided into five groups of 18 eyes. Groups 1–4 underwent epi-off CXL using a dextran-based riboflavin solution and an irradiance of 18 mW/cm2, group 5 served as the control group. Groups 1 to 4 were treated with a total fluence of 20, 15, 10.8, and 5.4 J/cm2, respectively. Thereafter, biomechanical measurements were performed on 5 mm wide and 6 mm long strips using an uniaxial material tester. Pachymetry measurements were performed on each cornea.

Results

At 10% strain, the stress was 76, 56, 52, and 31% higher in groups 1–4, respectively compared to the control group. The Young’s modulus was 2.85 MPa for group 1, 2.53 MPa for group 2, 2.46 MPa for group 3, 2.12 MPa for group 4, and 1.62 MPa for the control group. The difference between groups 1 to 4 and the control group 5 were statistically significant (p = <0.001; p = <0.001; p = <0.001; p = 0.021). In addition, group 1 showed significantly more stiffening than group 4 (p = <0.001), no other significant differences were found. Pachymetry measurements revealed no statistically significant differences among the five groups.

Conclusion

Additional mechanical stiffening can be achieved by increasing the fluence of the CXL. There was no threshold detected up to 20 J/cm2. A higher fluence could compensate the weaker effect of accelerated or epi-on CXL procedures.

Disclosure statement

Dr. Seiler is a scientific advisor for Avedro/Glaukos and receives material support for research projects. The other authors report no conflicts of interest.

Data availability statement

The data that support the findings of this study are available from the corresponding author, [IF], upon reasonable request.