Biomechanical analysis of different retreatment options after SMILE refractive surgery

Session Details

Session Title: Corneal Biomechanics

Session Date/Time: Monday 09/10/2017 | 08:00-10:30

Paper Time: 09:08

Venue: Room 2.1

First Author: : B.Spiru GERMANY

Co Author(s): :    S. Kling   F. Hafezi   W. Sekundo              

Abstract Details

Purpose:

To determine the corneal weakening induced by different re-treatment options after SmILE, and to investigate the potential of corneal cross-linking (CXL) to re-establish the original corneal stress resistance.

Setting:

Sabine Kling*1, Bogdan Spiru*2, Farhad Hafezi 3,4, Walter Sekundo 2 1 Laboratory of Ocular Cell Biology, University of Zurich, Zurich, Switzerland 2 Department of Ophthalmology, Philipps University of Marburg, Marburg, Germany 3 ELZA Institute, Dietikon/Zurich, Switzerland 4 University of Southern California, Los Angeles, CA, USA

Methods:

96 freshly enucleated porcine corneas were used. The initial refractive correction was defined to be -11D, the required enhancement to be -3D. Three different retreatment options were analyzed: (i) Re-SmILE, (ii) PRK on top of the SmILE cap and (iii) cap-to-flap conversion and excimer ablation on the stromal bed (“LASIK”). The (iv) control condition did not receive any treatment. Subsequently, accelerated CXL (9mW/cm2, 10min) was performed in two groups with currently common enhancement techniques: (v) following cap-to-flap conversion (“LASIK” enhancement) and (vi) in controls. Biomechanical properties were measured with stress-strain extensometry in the range from 1.27 to 12.5N.

Results:

The Re-SmILE and PRK enhancement did not significantly reduce the overall elastic modulus of the cornea compared to controls (24.7+/-2.23 MPa and 22.7+/-2.61 MPa versus 23.8+/-3.35 MPa, p>/=0.176), while LASIK enhancement did (22.2+/-3.37 MPa, p=0.048). CXL treatment significantly increased the elastic modulus compared to all non-cross-linked conditions (p

Conclusions:

In enhancement, the corneal biomechanical integrity is less affected with both, Re-SMILE and PRK enhancement. Corneal weakening through laser refractive surgery is small compared to the stiffening effect after CXL.

Financial Disclosure:

receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented