Tomographic and Biomechanical Scheimpflug Imaging for Keratoconus Characterization: A Validation of Current Indices

TY - JOUR

T1 - Tomographic and Biomechanical Scheimpflug Imaging for Keratoconus Characterization: A Validation of Current Indices

AU - Steinberg, Johannes

AU - Siebert, Marlene

AU - Katz, Toam Rahamim

AU - Frings, Andreas

AU - Mehlan, Juliane

AU - Druchkiv, Vasyl

AU - Bühren, Jens

AU - Linke, Stephan

PY - 2018/10/12

Y1 - 2018/10/12

N2 - PURPOSE:To analyze the potential benefit of the newly developed Tomography and Biomechanical Index (TBI) for early keratoconus screening.METHODS:In this retrospective study, the discriminatory power of the corneal tomography Belin/Ambrósio Enhanced Ectasia Display (BAD-D) index and the newly developed Corvis Biomechanical Index (CBI) and TBI to differentiate between normal eyes, manifest keratoconus eyes (KCE), very asymmetric keratoconus eyes with ectasia (VAE-E), and their fellow eyes with either regular topography (VAE-NT) or regular topography and tomography (VAE-NTT) were analyzed by applying the t test (for normal distribution), Wilcoxon matched-pairs test (if not normally distributed), and receiver operating characteristic curve (ROC). The DeLong test was used to compare the area under the ROC (AUROC). Further, the cut-offs of the analyzed indices presented in a study by Ambrósio et al. from 2017 were applied in the study population to enable a cross-validation in an independent study population.RESULTS:All indices demonstrated a high discriminative power when comparing normal and advanced keratoconus, which decreased when comparing normal and VAE-NT eyes and further when analyzing normal versus VAE-NTT eyes. The difference between the AUROCs reached a statistically significant level when comparing TBI versus BAD-D analyzing normal versus all included keratoconic eyes (P = .02). The TBI presented with the highest AUROCs throughout all conducted analyses when comparing different keratoconus stages, although not reaching a statistically significant level. Applying the cut-offs presented by Ambrósio et al. to differentiate between normal and VAE-NT in the study population, the accuracy was reproducible (accuracy in our study population with an optimized TBI cut-off: 0.72, with the cut-off defined by Ambrósio et al. 0.67).CONCLUSIONS:The TBI enables karatoconus screening in topographical and tomographical regular keratoconic eyes. To further improve the screening accuray, prospective studies should be conducted.

AB - PURPOSE:To analyze the potential benefit of the newly developed Tomography and Biomechanical Index (TBI) for early keratoconus screening.METHODS:In this retrospective study, the discriminatory power of the corneal tomography Belin/Ambrósio Enhanced Ectasia Display (BAD-D) index and the newly developed Corvis Biomechanical Index (CBI) and TBI to differentiate between normal eyes, manifest keratoconus eyes (KCE), very asymmetric keratoconus eyes with ectasia (VAE-E), and their fellow eyes with either regular topography (VAE-NT) or regular topography and tomography (VAE-NTT) were analyzed by applying the t test (for normal distribution), Wilcoxon matched-pairs test (if not normally distributed), and receiver operating characteristic curve (ROC). The DeLong test was used to compare the area under the ROC (AUROC). Further, the cut-offs of the analyzed indices presented in a study by Ambrósio et al. from 2017 were applied in the study population to enable a cross-validation in an independent study population.RESULTS:All indices demonstrated a high discriminative power when comparing normal and advanced keratoconus, which decreased when comparing normal and VAE-NT eyes and further when analyzing normal versus VAE-NTT eyes. The difference between the AUROCs reached a statistically significant level when comparing TBI versus BAD-D analyzing normal versus all included keratoconic eyes (P = .02). The TBI presented with the highest AUROCs throughout all conducted analyses when comparing different keratoconus stages, although not reaching a statistically significant level. Applying the cut-offs presented by Ambrósio et al. to differentiate between normal and VAE-NT in the study population, the accuracy was reproducible (accuracy in our study population with an optimized TBI cut-off: 0.72, with the cut-off defined by Ambrósio et al. 0.67).CONCLUSIONS:The TBI enables karatoconus screening in topographical and tomographical regular keratoconic eyes. To further improve the screening accuray, prospective studies should be conducted.

U2 - 10.3928/1081597X-20181012-01

DO - 10.3928/1081597X-20181012-01

M3 - SCORING: Journal article

VL - 34

JO - J REFRACT SURG

JF - J REFRACT SURG

SN - 1081-597X

IS - 12

M1 - 840

ER -