Corneal Biomechanical Metrics Using Dynamic Ultra-High-Speed Photography and Tomography Scheimpflug Camera to Distinguish Normal and Keratoconic Corneas

Friday, April 25, 2014
KIOSKS (Boston Convention and Exhibition Center)
Allan Luz, MD, Hospital de Olhos de Sergipe, Aracaju, Brazil
Isaac C. Ramos, MD, Hospital de Olhos Santa Luzia, Maceió-AL, Brazil
Bruno F. Valbon, MD, University of São Paulo, Niterói, Brazil
Bernardo T. Lopes, MD, Rio de Janeiro Corneal Tomography and Biomechanical Study Group, Rio de Janeiro, Brazil
Fernando Faria-Correia, MD, Hospital CUF, Porto, Portugal
Renato Ambrósio Jr., MD, PhD, Inst. Olhos R. Ambrósio, Rio de Janeiro, Brazil

Narrative Responses:

Purpose
To test the ability of tomography and corneal biomechanical metrics to distinguish normal from ectatic cases.

Methods
The Oculus Corvis ST (Oculus, Wetzlar, Germany) was used for assessing corneal biomechanics using ultra-high speed 8mm horizontal Scheimpflug camera taking 4,330 frames per second during non contact tonometry and . Pentacam Scheimpflug camera (Pentacam HR) was used to tomography data. Patients were classified based on clinical data, including Placido Topography (Atlas, Zeiss). Data from one eye randomly selected of 271 patients with topographically normal corneas (group N) and of 183 patients with bilateral keratoconus (group KC) were retrieved. The intraocular pressure, applanation and deformation responses were extracted.

Results
Combined parameter was calculated from the combination of these parameters using linear regressions by the BrAIn (Brazilian Artifical Intelligence on Corneal Tomography and Biomechanics) study group, in order to provide best possible separation of keratoconus and normals. Combined parameter had statistically significant distribution differences between Normal and Keratoconus. This parameter reached AUROC above 0,992.

Conclusion
Combined Corvis ST data and Pentacam data were effectively distinguish normal and ectatic corneas.