Corneal biomechanics: A diagnostic tool for differentiating high astigmatism and mild keratoconus

Background: High astigmatism (HA) can be misinterpreted as keratoconus (KCN), is highly prone to developing KCN and is normally reconfirmed using corneal topography. Aim: To determine the diagnostic value of corneal biomechanical parameters in distinguishing HA and normal eyes from mild KCN. Setti...

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Main Authors: Norsyariza Razak, Wan Haslina Wan Abdul Halim, Bariah Mohd-Ali
Format: Article
Language:English
Published: AOSIS 2025-01-01
Series:African Vision and Eye Health
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Online Access:https://avehjournal.org/index.php/aveh/article/view/953
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author Norsyariza Razak
Wan Haslina Wan Abdul Halim
Bariah Mohd-Ali
author_facet Norsyariza Razak
Wan Haslina Wan Abdul Halim
Bariah Mohd-Ali
author_sort Norsyariza Razak
collection DOAJ
description Background: High astigmatism (HA) can be misinterpreted as keratoconus (KCN), is highly prone to developing KCN and is normally reconfirmed using corneal topography. Aim: To determine the diagnostic value of corneal biomechanical parameters in distinguishing HA and normal eyes from mild KCN. Setting: This is a comparative retrospective study. Methods: This study assessed 55 eyes with mild KCN (stages I and II), 56 eyes with HA ( 2.0 DC) without KCN and 55 normal healthy eyes. Corneal biomechanical and tomography parameters were measured using the Corvis ST and Pentacam HR (Oculus Optikgeräte GmbH, Germany). Keratoconus was diagnosed through slit lamp examination and abnormal corneal tomography patterns. The Kruskal–Wallis test evaluated each parameter’s distinguishing capability, and the receiver operating characteristic curve (ROC) analyzed the ability to differentiate high astigmatism and normal eyes from mild KCN. Results: The Corvis biomechanical index (CBI) between HA and mild KCN reflected a lower area under the curve (AUC) of 0.859, with a sensitivity of 92.7% and specificity of 65.4%, than CBI between normal and mild KCN, with an AUC of 0.896. The AUC for the Belin / Ambrósio enhanced ectasia deviation index (BAD-D) was 0.993, while the tomographical and biomechanical index (TBI) achieved an AUC of 0.99. Conclusion: Scheimpflug-derived biomechanical parameters effectively differentiated suspected HA and normal corneas from mild KCN corneas, indicating that corneal stiffness decreases at the early KCN stage. Contribution: Oculus Corvis ST effectively screens for ectasia risk, enabling early detection of KCN in individuals with high astigmatism and asymmetric curvature.
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spelling doaj-art-fa0611c3ec4a4cccb32d1cc0e10343582025-02-11T13:23:00ZengAOSISAfrican Vision and Eye Health2413-31832410-15162025-01-01841e1e710.4102/aveh.v84i1.953618Corneal biomechanics: A diagnostic tool for differentiating high astigmatism and mild keratoconusNorsyariza Razak0Wan Haslina Wan Abdul Halim1Bariah Mohd-Ali2Department of Ophthalmology, Faculty of Medicine, National University of Malaysia, Kuala LumpurDepartment of Ophthalmology, Faculty of Medicine, National University of Malaysia, Kuala Lumpur, Malaysia; and, Faculty of Medicine and Health Sciences, UCSI University, Kuala LumpurOptometry and Vision Science Program, Faculty of Health Sciences, National University of Malaysia, Kuala LumpurBackground: High astigmatism (HA) can be misinterpreted as keratoconus (KCN), is highly prone to developing KCN and is normally reconfirmed using corneal topography. Aim: To determine the diagnostic value of corneal biomechanical parameters in distinguishing HA and normal eyes from mild KCN. Setting: This is a comparative retrospective study. Methods: This study assessed 55 eyes with mild KCN (stages I and II), 56 eyes with HA ( 2.0 DC) without KCN and 55 normal healthy eyes. Corneal biomechanical and tomography parameters were measured using the Corvis ST and Pentacam HR (Oculus Optikgeräte GmbH, Germany). Keratoconus was diagnosed through slit lamp examination and abnormal corneal tomography patterns. The Kruskal–Wallis test evaluated each parameter’s distinguishing capability, and the receiver operating characteristic curve (ROC) analyzed the ability to differentiate high astigmatism and normal eyes from mild KCN. Results: The Corvis biomechanical index (CBI) between HA and mild KCN reflected a lower area under the curve (AUC) of 0.859, with a sensitivity of 92.7% and specificity of 65.4%, than CBI between normal and mild KCN, with an AUC of 0.896. The AUC for the Belin / Ambrósio enhanced ectasia deviation index (BAD-D) was 0.993, while the tomographical and biomechanical index (TBI) achieved an AUC of 0.99. Conclusion: Scheimpflug-derived biomechanical parameters effectively differentiated suspected HA and normal corneas from mild KCN corneas, indicating that corneal stiffness decreases at the early KCN stage. Contribution: Oculus Corvis ST effectively screens for ectasia risk, enabling early detection of KCN in individuals with high astigmatism and asymmetric curvature.https://avehjournal.org/index.php/aveh/article/view/953corneal biomechanicsoculus corvis stkeratoconusmild keratoconushigh astigmatism.
spellingShingle Norsyariza Razak
Wan Haslina Wan Abdul Halim
Bariah Mohd-Ali
Corneal biomechanics: A diagnostic tool for differentiating high astigmatism and mild keratoconus
African Vision and Eye Health
corneal biomechanics
oculus corvis st
keratoconus
mild keratoconus
high astigmatism.
title Corneal biomechanics: A diagnostic tool for differentiating high astigmatism and mild keratoconus
title_full Corneal biomechanics: A diagnostic tool for differentiating high astigmatism and mild keratoconus
title_fullStr Corneal biomechanics: A diagnostic tool for differentiating high astigmatism and mild keratoconus
title_full_unstemmed Corneal biomechanics: A diagnostic tool for differentiating high astigmatism and mild keratoconus
title_short Corneal biomechanics: A diagnostic tool for differentiating high astigmatism and mild keratoconus
title_sort corneal biomechanics a diagnostic tool for differentiating high astigmatism and mild keratoconus
topic corneal biomechanics
oculus corvis st
keratoconus
mild keratoconus
high astigmatism.
url https://avehjournal.org/index.php/aveh/article/view/953
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AT wanhaslinawanabdulhalim cornealbiomechanicsadiagnostictoolfordifferentiatinghighastigmatismandmildkeratoconus
AT bariahmohdali cornealbiomechanicsadiagnostictoolfordifferentiatinghighastigmatismandmildkeratoconus