Quantitative assessment of responses of the eyeball based on data from the Corvis tonometer

Koprowski, Robert; Wilczyński, Sławomir; Nowińska, Anna; Lyssek-Boroń, Anita; Teper, Sławomir; Wylęgała, Edward; Wróbel, Zygmunt

doi:10.1016/j.compbiomed.2015.01.006

Cited by 12 publications

(16 citation statements)

References 44 publications

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“…However, many built‐in parameters of the CorVis ST cannot be utilized for diagnosis of keratoconus or to indicate the effect of CXL. For further research, Koprowski et al proposed a new method to provide additional corneal deformation parameters which were not available in the built‐in software of CorVis ST. Besides, they developed open source software to further assess corneal response such as corneal deformation, eyeball reaction and corneal vibration.…”

Section: Discussionmentioning

confidence: 99%

Determining in vivo elasticity and viscosity with dynamic Scheimpflug imaging analysis in keratoconic and healthy eyes

Wang

Tian

Zheng

2016

Journal of Biophotonics

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The paper presents a novel analysis method of corneal elasticity and viscosity based on corneal visualization Scheimpflug technology (CorVis ST) for keratoconus diagnosis. Methods for air puff force measurement and corneal imaging boundary extraction were proposed. Corneal biomechanical properties, described as tangent stiffness coefficient (STSC ) and energy absorbed area (Aabsorbed ), were assessed using the curves of the applied air puff force with corneal displacement to form a loading-unloading cycle. Twenty-five patients with keratoconus and 34 healthy control subjects, matched for intraocular pressure (IOP), were enrolled in this prospective study. The results showed that the intraclass correlation coefficients (ICC) of the STSC and Aabsorbed were 0.941 and 0.878 in Healthy group; and were 0.891 and 0.809 in Keratoconus group, respectively. Both STSC and Aabsorbed of keratoconus patients were significantly different from that of controls (both probability value P< 0.001). ROC curve analysis showed that the area under curve for STSC was 0.918 and for Aabsorbed was 0.894, which reached a good level of predictive accuracy for detecting keratoconus. Our results demonstrated that this new analysis method could be used to characterize the biomechanical properties of corneas. (a) The air puff force of CorVis ST was measured by a custom-designed force detection system. (b) Corneal displacement was extracted from CorVis ST using a proposed imaging analysis. (c) With the utilization of the air puff force and corneal dynamic displacement, an analysis method was developed to introduce new corneal biomechanical parameters - STSC and Aabsorbed .

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Section: Discussionmentioning

confidence: 99%

Determining in vivo elasticity and viscosity with dynamic Scheimpflug imaging analysis in keratoconic and healthy eyes

Wang

Tian

Zheng

2016

Journal of Biophotonics

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“…Filtration with median filter was performed with the use of h MED mask of the size M MED × N MED = 3 × 3 pixels [40]. The output image L MED ( m , n , i ) was further normalized i.e.…”

Section: Methods and Resultsmentioning

confidence: 99%

A clinical utility assessment of the automatic measurement method of the quality of Meibomian glands

2017

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BackgroundMeibomian gland dysfunction (MGD) is one of the most common diseases observed in clinics and is the leading cause of evaporative dry eye. Today, diagnostics of MGD is not fully automatic yet and is based on a qualitative assessment made by an ophthalmologist. Therefore, an automatic analysis method was developed to assess MGD quantiatively.MaterialsThe analysis made use of 228 images of 57 patients recorded by OCULUS Keratograph® 5 M with a resolution of 1024 × 1360 pixels concern 30 eyes of healthy individuals (14 women and 16 men) and 27 eyes of sick patients (10 women and 17 men). The diagnosis of dry eye was made according to the consensus of DED in China (2013).MethodsThe presented method of analysis is a new, developed method enabling an automatic, reproducible and quantitative assessment of Meibomian glands. The analysis relates to employing the methods of analysis and image processing. The analysis was conducted in the Matlab environment Version 7.11.0.584, R2010b, Java VM Version: Java 1.6.0_17-b04 with Sun Microsystems Inc. with toolboxes: Statistical, Signal Processing and Image Processing.ResultsThe presented, new method of analysis of Meibomian glands is fully automatic, does not require operator’s intervention, allows obtaining reproducible results and enables a quantitative assessment of Meibomian glands. Compared to the other known methods, particularly with the method described in literature it allows obtaining better sensitivity (98%) and specificity (100%) results by 2%.

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“…Few papers have been published so far in this area. These include the papers of Tejwani et al [ 51 ] and Koprowski et al [ 52 – 54 ]. The first one ( [ 51 ]) refers to spectral analysis and comparison of the ORA with the Corvis tonometer.…”

Section: Introductionmentioning

confidence: 99%

“…The first one ( [ 51 ]) refers to spectral analysis and comparison of the ORA with the Corvis tonometer. The second and third papers ( [ 52 , 54 ]) present the analysis of new features (e.g. reaction of the eyeball) obtained from the image analysis method proposed by the authors.…”

Section: Introductionmentioning

confidence: 99%

Automatic method of analysis and measurement of additional parameters of corneal deformation in the Corvis tonometer

Koprowski

2014

BioMed Eng OnLine

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IntroductionThe method for measuring intraocular pressure using the Corvis tonometer provides a sequence of images of corneal deformation. Deformations of the cornea are recorded using the ultra-high-speed Scheimpflug camera. This paper presents a new and reproducible method of analysis of corneal deformation images that allows for automatic measurements of new features, namely new three parameters unavailable in the original software.Material and methodThe images subjected to processing had a resolution of 200 × 576 × 140 pixels. They were acquired from the Corvis tonometer and simulation. In total 14000 2D images were analysed. The image analysis method proposed by the author automatically detects the edge of the cornea and sclera fragments. For this purpose, new methods of image analysis and processing proposed by the author as well as those well-known, such as Canny filter, binarization, median filtering etc., have been used. The presented algorithms were implemented in Matlab (version 7.11.0.584 - R2010b) with Image Processing toolbox (version 7.1 -R2010b) using both known algorithms for image analysis and processing and those proposed by the author.ResultsOwing to the proposed algorithm it is possible to determine three parameters: (1) the degree of the corneal reaction relative to the static position; (2) the corneal length changes; (3) the ratio of amplitude changes to the corneal deformation length. The corneal reaction is smaller by about 30.40% compared to its static position. The change in the corneal length during deformation is very small, approximately 1% of its original length. Parameter (3) enables to determine the applanation points with a correlation of 92% compared to the conventional method for calculating corneal flattening areas. The proposed algorithm provides reproducible results fully automatically within a few seconds/per patient using Core i7 processor.ConclusionsUsing the proposed algorithm, it is possible to measure new, additional parameters of corneal deformation, which are not available in the original software. The presented analysis method provides three new parameters of the corneal reaction. Detailed clinical studies based on this method will be presented in subsequent papers.

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Quantitative assessment of responses of the eyeball based on data from the Corvis tonometer

Cited by 12 publications

References 44 publications

Determining in vivo elasticity and viscosity with dynamic Scheimpflug imaging analysis in keratoconic and healthy eyes

Determining in vivo elasticity and viscosity with dynamic Scheimpflug imaging analysis in keratoconic and healthy eyes

A clinical utility assessment of the automatic measurement method of the quality of Meibomian glands

Automatic method of analysis and measurement of additional parameters of corneal deformation in the Corvis tonometer

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