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Corneal Biomechanical Assessment using Dynamic Ultra High-Speed (UHS) Scheimpflug Imaging and Non-Contact Tonometry PowerPoint Presentation
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Corneal Biomechanical Assessment using Dynamic Ultra High-Speed (UHS) Scheimpflug Imaging and Non-Contact Tonometry - PowerPoint PPT Presentation


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Corneal Biomechanical Assessment using Dynamic Ultra High-Speed (UHS) Scheimpflug Imaging and Non-Contact Tonometry (NCT) . Diogo L. Caldas, MD Isaac C. Ramos, MD Renato Ambrósio Jr, MD, PhD Michael W. Belin, MD, FACS Cynthia J. Roberts, PhD.

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slide1

Corneal Biomechanical Assessment using Dynamic Ultra High-Speed (UHS)

Scheimpflug Imaging

and Non-Contact Tonometry (NCT)

Diogo L. Caldas, MD

Isaac C. Ramos, MD

Renato Ambrósio Jr, MD, PhD

Michael W. Belin, MD, FACS

Cynthia J. Roberts, PhD

Dr. Ambrósio, Dr. Belin and Dr. Roberts are consultants for Oculus Optikgeräte GmbH (Wetzlar, Germany)

slide2

Purpose

  • To present CorVis ST (Oculus, Wetzlar) - a new clinical tool for assessment of corneal biomechanical properties and intraocular pressure (IOP)
  • To test its capability to distinguish different materials based on their deformation characteristics

Oculus CorVis ST

  • Ultra High-Speed (UHS ST)
  • Scheimpflug Technology: 4,330 frames/sec
  • 8mm horizontal coverage
  • NCT symmetrically metered air pulse
slide3

Methods: Contact Lens Experiment

  • Three hydrophilic contact lenses:
    • TAN-40: 62% Hydroxyethylmethacrylate (525µm thick)
    • TAN-58: 42% Methylmethacrylate (258µm thick)
    • TAN-G5X: 41% Hydroxyethylmethacrylate/Glycolmethacrylate, (550µm thick)
  • Mounted on a water chamber with adjustable pressures
slide4

Methods: Contact Lens Experiment

  • Pressures from 0 to 70mmHg (5mmHg intervals)
  • 6 measurements for each lens at each pressure level

MAIN OUTCOME MEASURES

  • Deformation amplitude (DA- highest concavity displacement of the apex)
  • Corneal speed and curvature
  • Time for the highest concavity momentum
  • Curvature at highest concavity momentum
slide5

Response is influenced by the Pressure at the Chamber

Contact Lens Experiment

TAN 40 at 0mmHg adjusted chamber pressure

Contact Lens Experiment

TAN 40 at 20mmHg adjusted chamber pressure

Contact Lens Experiment

TAN 40 at 60mmHg adjusted chamber pressure

slide7

Results: Deformation amplitude

  • DA: Highest concavity displacement of the apex

Contact Lens Experiment

Measurements at 20mmHg adjusted IOP

Coef. Of Variability < 5%

slide8

Response is influenced by the Pressure at the Chamber

TAN 40

at 0mmHg adjusted chamber pressure

TAN 58

at 60mmHg adjusted chamber pressure

slide9

Results: Highest Concavity

  • Time of highest concavity momentum (HC Time)
  • Curvature at highest concavity momentum (Cur HC)
slide10

Conclusions from Contact Lens Experiment

  • Dynamic UHS Scheimpflug corneal imaging with NCT enables to differentiate physical properties in test objects based on deformation response
  • The response is influenced by the material properties and by chamber pressure
  • The inspection of the actual deformation process provides further detailing for corneal characterization
  • Relevance for Cornea, Refractive Surgery, Glaucoma…
slide11

Thank You !

diogolcaldas@gmail.com