Scheimpflug camera in the quantitative assessment of reproducibility of high‐speed corneal deformation during intraocular pressure measurement

Koprowski, Robert; Ambrósio, Renato; Reisdorf, Sven

doi:10.1002/jbio.201400137

Cited by 21 publications

(25 citation statements)

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“…The presented software is currently used in a number of ophthalmic clinics in the world providing new diagnostic quality which is not available in the original software of the Corvis tonometer [ 21 - 25 ]. In particular it enables 3D visualization of the corneal deformation and eyeball response.…”

Section: Resultsmentioning

confidence: 99%

“…These are new parameters that are measured irrespective of the software of the Corvis tonometer. The various parameters and methods of their measurement have been described in five publications by Koprowski R. [ 21 - 25 ] and are not cited here. The exact list of these publications and additional measurable parameters that are not available in the original software of the Corvis tonometer are shown in Table 1 .…”

Section: Introductionmentioning

confidence: 99%

“…A detailed description of the proposed software is provided in the following sections while the description of the methods of measurement of individual parameters and their diagnostic significance have been described in detail in the aforementioned previous works of the author [ 21 - 25 ].…”

Section: Introductionmentioning

confidence: 99%

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Open source software for the analysis of corneal deformation parameters on the images from the Corvis tonometer

Koprowski

2015

BioMed Eng OnLine

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BackgroundThe software supplied with the Corvis tonometer (which is designed to measure intraocular pressure with the use of the air-puff method) is limited to providing basic numerical data. These data relate to the values of the measured intraocular pressure and, for example, applanation amplitudes. However, on the basis of a sequence of images obtained from the Corvis tonometer, it is possible to obtain much more information which is not available in its original software. This will be presented in this paper.Material and methodThe proposed software has been tested on 1400 images from the Corvis tonometer. The number of analysed 2D images (with a resolution of 200 × 576 pixels) in a sequence is arbitrary. However, in typical cases there are 140 images. The proposed software has been written in Matlab (Version 7.11.0.584, R2010b). The methods of image analysis and processing and in particular edge detection and the fast Fourier transform have been applied.Results and discussionThe software allows for fully automatic (1) acquisition of 12 new parameters previously unavailable in the original software of the Corvis tonometer. It also enables off-line (2) manual and (3) automatic browsing of images in a sequence; 3D graph visualization of: (4) the corneal deformation and (5) eyeball response; 6) change of the colour palette; (7) filtration and (8) visualization of selected measured values on individual 2D images. In addition, the proposed software enables (9) to save the obtained results for further analysis and processing.ConclusionsThe dedicated software described in this paper enables to obtain additional new features of corneal deformations during intraocular pressure measurement. The software can be applied in the diagnosis of corneal deformation vibrations, glaucoma diagnosis, evaluation of measurement repeatability and others. The software has no licensing restrictions and can be used both commercially and non-commercially without any limitations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12938-015-0027-3) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Open source software for the analysis of corneal deformation parameters on the images from the Corvis tonometer

Koprowski

2015

BioMed Eng OnLine

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“…A whole set of corneal deformation parameters is provided. 32,33 The Oculus CorVis ST imaging system is based on the instrument we used for this study and has been the subject of many studies in the characterization of corneal biomechanical properties. [34][35][36] In this study, we analyzed in vivo corneal biomechanical properties from corneal deformation during NCT using the prototype of the CorVis ST.…”

Section: Discussionmentioning

confidence: 99%

Corneal Deformation Response with Dynamic Ultra-high-speed Scheimpflug Imaging for Detecting Ectatic Corneas

Ramos¹,

Salomão²,

Correia³

2016

International Journal of Keratoconus and Ectatic Corneal Diseases

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Purpose:To test the ability of metrics derived from corneal response to noncontact tonometry (NCT) to distinguish between normal and ectatic cases. Materials and methods:The prototype of CorVis ST (Oculus, Wetzlar, Germany) was used for assessing corneal biomechanical response using ultra-high-speed 8 mm horizontal Scheimpflug photography, taking 4,330 frames per second during NCT. Patients were stratified based on clinical data, including rotating Scheimpflug corneal tomography (Oculus Pentacam HR). Biomechanical data from one eye randomly selected of 177 patients with normal corneas (N) and from 79 patients with bilateral keratoconus (KC) were investigated. Group forme fruste keratoconus (FFKC) was composed of 20 eyes with normal topographic patterns from cases with ectasia detected in the fellow eye. Group keratoconus suspect (KCS) had 16 eyes from 16 patients with topographic patterns suspicious of KC but documented stability over 3 years and normal tomographic findings. A combination of deformation parameters using linear regression analysis (Prototype Factor 1, pF1) was created by the BrAIn (Brazilian Artificial Intelligence on Corneal Tomography and Biomechanics) study group in order to provide the best possible separation of KC and normals.Results: Statistical significant differences were found for N × KC for several parameters, including first and second applanation times, deformation amplitude, and maximal concavity radius (Mann-Whitney, p < 0.001). However, the areas under the receiver operating characteristic curves (AUC) were lower than 0.90. The pF1 had AUC of 0.945 (IC 0.909-0.97; sensitivity = 87.3% and specificity = 89.3%). The pF1 had statistically significant differences between the ectatic (KC and FFKC) and nonectatic groups (N and KCS) (p < 0.05, Kruskall-Wallis Test with post hoc Dunn's test). Conclusion:Corneal deformation response analysis by ultrahigh-speed 8 mm horizontal Scheimpflug photography provides relevant data for distinguishing ectatic and nonectatic corneas but cannot be used independently to detect KC. This data may be integrated with corneal tomography data for enhancing sensitivity and specificity for screening ectasia.

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“…It employs an ultra high-speed Scheimpflug camera that records the deformation process at 4330 frames/second along an 8 mm horizontal corneal cross-section during corneal deformation. 15,16 Analysis of the images provides insight into the infrared signal behavior observed with the ORA, and because direct analysis of shape is possible, provides additional opportunities for a more direct derivation of biomechanical response. 17,18 Contrary to the ORA, the Corvis STL does not vary the air puff pressure from measurement to measurement.…”

Section: Clinical Measurements Of Corneal Biomechanicsmentioning

confidence: 99%

Biomechanical Diagnostics of the Cornea

Stefano

Dupps

2017

International Ophthalmology Clinics

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Biomechanics is the science concerned with the origin and effects of forces that act on living organisms. The cornea is a complex composite whose behavior depends on its structural subcomponents and their organizational motifs. A better understanding of its biomechanical features is essential to understand the consequences of procedures such excimer laser refractive surgery and corneal collagen crosslinking and to improve the detection and management of ectatic corneal diseases. Devices such as the Ocular Response Analyzer and the Corvis STL use an air-puff to perturb the cornea and assess biomechanical responses. Although both devices use similar approaches, data produced by them cannot be used interchangeably. Moreover, current commercial technologies lack capabilities for regional property discrimination, which is of paramount importance for comprehensive biomechanical analysis. To address this gap, other methodologies such as optical coherence elastography and Brillouin microscopy are being developed and early in vivo studies show promising results. Finally, another important tool for studying complex structures is computational modeling using the finite element method. The cornea can be represented as a mesh of smaller geometric elements with specific material properties. Advances in this area have the potential to enhance diagnosis, enable personalized risk assessment, and optimize treatment design toward the goal of improving safety and outcomes for corneal and refractive surgery patients.

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Scheimpflug camera in the quantitative assessment of reproducibility of high‐speed corneal deformation during intraocular pressure measurement

Cited by 21 publications

References 54 publications

Open source software for the analysis of corneal deformation parameters on the images from the Corvis tonometer

Open source software for the analysis of corneal deformation parameters on the images from the Corvis tonometer

Corneal Deformation Response with Dynamic Ultra-high-speed Scheimpflug Imaging for Detecting Ectatic Corneas

Biomechanical Diagnostics of the Cornea

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