Corneal Biomechanics in Ectatic Diseases: Refractive Surgery Implications

Renato Ambrósio, Jr1, 2, 3, 4, 5, *, Fernando Faria Correia6, 7, 8, Bernardo Lopes1, 2, 3, 4, 5, Marcella Q. Salomão1, 2, 3, 4, 5, Allan Luz3, 4, 5, Daniel G. Dawson9, Ahmed Elsheikh10, 11, Riccardo Vinciguerra12, Paolo Vinciguerra12, 13, Cynthia J. Roberts14
1 Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
2 VisareRIO, Rio de Janeiro, Brazil
3 Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
4 Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BRAIN, Rio de Janeiro & Maceió, Brazil
5 Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
6 Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
7 ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
8 Ophthalmology Department, Hospital de Braga, Braga, Portugal.
9 The University of Florida Department of Ophthalmology, Gainesville, FL, USA
10 School of Engineering, University of Liverpool – Liverpool, United Kingdom
11 NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, UK
12 Department of Surgical Sciences, Division of Ophthalmology, University of Insubria, Varese, Italy
13 Eye Center, Humanitas Clinical and Research Center, Via Manzoni 56, Rozzano (MI) – Italy
14 Department of Ophthalmology & Visual Science, Department of Biomedical Engineering, The Ohio State University – Columbus, OH, USA

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Creative Commons License
© 2017 Ambrósio et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Rua Conde de Bonfim 211 / 712 20520-050 - Rio de Janeiro RJ - Brazil, Tel: 55-21-22745694; E-mail:



Ectasia development occurs due to a chronic corneal biomechanical decompensation or weakness, resulting in stromal thinning and corneal protrusion. This leads to corneal steepening, increase in astigmatism, and irregularity. In corneal refractive surgery, the detection of mild forms of ectasia pre-operatively is essential to avoid post-operative progressive ectasia, which also depends on the impact of the procedure on the cornea.


The advent of 3D tomography is proven as a significant advancement to further characterize corneal shape beyond front surface topography, which is still relevant. While screening tests for ectasia had been limited to corneal shape (geometry) assessment, clinical biomechanical assessment has been possible since the introduction of the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, USA) in 2005 and the Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) in 2010. Direct clinical biomechanical evaluation is recognized as paramount, especially in detection of mild ectatic cases and characterization of the susceptibility for ectasia progression for any cornea.


The purpose of this review is to describe the current state of clinical evaluation of corneal biomechanics, focusing on the most recent advances of commercially available instruments and also on future developments, such as Brillouin microscopy.