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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

Purpose:

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

Setting:

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

Methods:

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.

Results:

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.

Conclusions:

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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