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Integration of Scheimpflug-based corneal tomography and biomechanical assessments for enhancing ectasia detection

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Session Details

Session Title: Moderated Poster Session: New and Interesting

Venue: Poster Village: Pod 1

First Author: : R.Ambrosio BRAZIL

Co Author(s): :    B. Lopes   J. Buhren   C. Roberts   A. Elsheikh   R. Vinciguerra   P. Vinciguerra

Abstract Details


To present the Tomographic/Biomechanical Index (TBI), that combines Scheimpflug-based corneal tomography and biomechanics for enhancing ectasia detection.


1. Rio de Janeiro Corneal Tomography and Biomechanics Study Group 2. Federal University of São Paulo 3. Eye Center, Humanitas Clinical and Research Center, Via Manzoni 56, Rozzano (MI); Italy


Patients from different continents were studied. One eye randomly selected from 480 patients with normal corneas and from 204 keratoconus patients comprised groups I and II respectively. Group III included 72 non-operated ectatic eyes from 94 patients with very asymmetric ectasia, whose fellow eyes (group IV) presented with normal topography. Pentacam HR and Corvis ST (OCULUS; Wetzlar, Germany) parameters were analyzed and combined using different artificial intelligence methods (AI). The accuracies for detecting ectasia of BAD-D (Belin/Ambrósio Deviation) and CBI (Corvis Biomechanical Index) were compared to TBI, considering the areas under receiver operating characteristic curves (AUROC).


The random forest method with leave-one-out cross-validation (RF/LOOCV) provided the best AI model. The AUROC for detecting ectasia (groups II, III and IV) of TBI was 0.996, being statistically higher (DeLong, p<0.001) than BAD-D (0.956) and CBI (0.936). TBI cutoff value of 0.79 provided 100% sensitivity for detecting clinical ectasia (groups II and III) with 100% specificity. Considering group IV, AUROC for TBI, BAD-D and CBI were 0.985, 0.839 and 0.822 (DeLong, p<0.001). An optimized TBI cutoff value of 0.29 provided 90.4% sensitivity in group IV, with 96% specificity.


TBI generated by RF/LOOCV provides accuracy for detecting ectasia, exceeding other techniques. TBI is sensitive for detecting sub-clinical (fruste) ectasia among eyes with normal topography in very asymmetric patients. TBI may also confirm unilateral disease, potentially characterizing the inherent ectasia susceptibility of the cornea.

Financial Disclosure:

gains financially from product or procedure presented, is employed by a for-profit company with an interest in the subject of the presentation

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