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Scheimpflug biomechanical and integrated indices in patients with abnormal tomography in both eyes but no keratoconus sign based on clinical or topographic assessments

Poster Details

First Author: S.Maeno JAPAN

Co Author(s):    S. Koh   R. Inoue   R. Ambrósio Jr   N. Maeda   K. Nishida        

Abstract Details


Corneal tomographic and biomechanical indices were demonstrated to enhance detection of subclinical ectasia in eyes with normal topography in patients with very asymmetric ectasia. However, subclinical ectasia or its high susceptibility could be present when both eyes have normal front surface topography. The purpose of this study is to report the biomechanical and integrated Scheimpflug assessments in patients with both eyes presenting abnormal corneal tomographic evaluation, but with no clinical keratoconus (KC) sign and bilateral normal topography.


Osaka University Hospital, Osaka, Japan


We retrospectively reviewed the clinical records of patients referred for abnormal refraction. Inclusion criteria were; no clinical KC sign with normal topography based on objective criteria by TMS-5 (Tomey) with 0% similarity (Klyce/Maeda) and 0% severity (Smolek/Klyce) in both eyes, but at least one of the eyes had abnormal Scheimpflug-based corneal tomography with Pentacam HR (Oculus GmbH) based on thickness or elevation on the Belin/Ambrósio Display. Corneal biomechanical assessment was performed with the Corvis ST (Oculus GmbH). The Corvis Biomechanical Index (CBI) and Tomographic and Biomechanical Index (TBI) were analyzed along with the Pentacam Random Forest Index (PRFI).


Thirteen patients met the objective inclusion criteria for abnormal tomography of either Belin/Ambrósio Deviation >1.6, Ambrósio’s relational thickness (ART)max<412, ARTave<513, or back surface elevation at the thinnest point using the 8-mm best fit sphere > 15microns. Among the 26 eyes of 13 cases, based on the currently published criteria for ectasia susceptibility, 17 eyes of 10 cases (abnormal group) were abnormal in at least one of the criteria of CBI > 0.5 (1 case, 7.7%), or TBI > 0.29 (6 cases 9 eyes, 46.2%), and PRFI >0.125 (10 cases 17 eyes, 76.9%).


The integration of data beyond corneal shape including the biomechanical and integrated parameters enhances the ability to confirm ectasia in patients presenting bilateral normal slit-lamp observations with normal topography. Advanced analysis as an attempt to enhance the ability to determine the abnormality is useful in most cases with the abnormal tomography. Longitudinal observation is needed for these cases along with larger cohorts.

Financial Disclosure:

... gains financially from product or procedure presented

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