Copenhagen 2016 Registration Programme Exhibitor Information Virtual Exhibition Satellite Meetings Glaucoma Day 2016 Hotel Star Alliance

10 - 14 Sept. 2016, Bella Center, Copenhagen, Denmark

This Meeting has been awarded 27 CME credits


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Biomechanical differences between FLEx and SMILE refractive procedures from 2D-extensiometry in ex-vivo porcine eyes

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Session Details

Session Title: Presented Poster Session: Corneal Biomechanics

Session Date/Time: Saturday 10/09/2016 | 15:00-16:30

Paper Time: 16:00

Venue: Poster Village: Pod 4

First Author: : B.Spiru GERMANY

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

Abstract Details


To evaluate the biomechanical stability of ex vivo porcine corneas after FLEx and SMILE refractive surgeries.


1. Laboratory of Experimental Ophthalmology, Department of Ophthalmology, University Hospital of Marburg, Germany 2. Laboratory of Ocular Cell Biology, Department of Clinical Neurosciences, University Hospitals of Zurich, Switzerland


45 porcine eyes were equally divided into 3 groups: Group1 was treated with FLEx procedure, group2 with SMILE procedure. Group3 were left untreated and served as controls. Because porcine corneas are thicker than human corneas groups 1 and 2 received refractive correction of -14D with 7mm zone using either 160µm flap or 160µm cap. For 2D-biomechanical measurements, corneo-scleral buttons were excised. Three testing cycles (pre-conditioning from 1.27 to 12.5N, stress-relaxation at 12.5N during 120s, stress-strain curve up to 25N) were performed in order to analyze elastic and viscoelastic material properties. Young’s modulus and Prony constants were calculated.


At 0.8% of strain, FLEx (370±36 kPa) could resist a significantly lower stress than SMILE (392±19 kPa, P=0.046) and the control group (402±30 kPa, P=0.013). Also, FLEx (46.1±4.5 MPa) had a significantly lower Young’s modulus than the control group (50.2±3.4 MPa, P=0.008). The Young’s modulus of SMILE (48.6±2.5 MPa) had values situated between untreated corneas and FLEx treated corneas, but the difference did not reach the level of statistical significance in comparison to FLEx (P=0.065) or controls (P=0.159). Compared to untreated controls, the stress resistance decreased by 8.0% with FLEx and 2.5% with SMILE; Young’s modulus decreased by 5.1% with FLEx and 1.04% with SMILE.


Compared to flap-based procedures like FLEx, the SMILE technique can be considered superior in terms of biomechanical stability, when measured experimentally in porcine corneas.

Financial Disclosure:

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

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