1 / 10

Mathematical Analysis of 150-Degree Femtosecond Reverse Bevel

Mathematical Analysis of 150-Degree Femtosecond Reverse Bevel. James S. Lewis, MD I have no financial interest in the subject matter of this poster. ASCRS 2011. Motivation for this Study. Inverted Bevel-In Side Cut Inverted bevel-in side cut promotes flap stability and positioning. 1,2

xanthe
Download Presentation

Mathematical Analysis of 150-Degree Femtosecond Reverse Bevel

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mathematical Analysis of 150-Degree Femtosecond Reverse Bevel James S. Lewis, MD I have no financial interest in the subject matter of this poster ASCRS 2011

  2. Motivation for this Study • Inverted Bevel-In Side Cut • Inverted bevel-in side cut promotes flap stability and positioning. 1,2 • Enhanced biomechanical stability of the post-LASIK cornea Promotional literature on Femtosecond Vendor’s Website

  3. Geometric Implications Assuming this is a standard 8.5 mm corneal flap with a thickness of 100 microns

  4. Geometric Reality Assuming this is a standard 8.5 mm corneal flap with a thickness of 100 microns

  5. Using Computer Assisted Design Assuming 50 microns of epithelium and 110 micron flap

  6. Assessment of True Geometry

  7. True Representation of the Geometry

  8. Total Region of Enhanced Support

  9. Greater Support • 1.5% overhang • Average Manhole cover has 3.5 % overhang • Total area of peripheral contact correlates to wound strength • 150 degree bevel increases wound strength only 20%

  10. Another Problem with the Bevel • Myopic ablation reduces the length of the path (non-Euclidean distance) from one end of the stromal bed to the other. • There is no such foreshortening of the flap • Consequently, there is as much as 100 microns of “excess” flap length. • Two point fixation (hinge and bevel apex) allows for no degrees of freedom • A 150 degree bevel will generate striae from poor flap-stromal bed apposition* *the formal proof is being prepared for submission

More Related