Overview of the Ocular Biomechanical Properties Measured by the Ocular Response Analyzer and the Corvis ST

Jędzierowska, Magdalena; Koprowski, Robert; Wróbel, Zygmunt

doi:10.1007/978-3-319-06596-0_35

Cited by 8 publications

(9 citation statements)

References 28 publications

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“…In the Corvis ST tonometer, the basics of biomechanical parameters measurements are based on the analysis of the dynamic corneal deformation recorded by the ultra-fast Scheimpflug camera. Thanks to the possibility of reconstructing the full process of corneal deformation and observation of its dynamic changes in the video, the Corvis ST tonometer allows to obtain a much bigger number of quantitative parameters that are the basis for the description of biomechanical changes during the examination [32–36]. Various methods of image analysis and processing [37–39], or artificial intelligence methods and others [40–42] can be applied for this purpose.…”

Section: Introductionmentioning

confidence: 99%

Novel dynamic corneal response parameters in a practice use: a critical review

Jędzierowska

Koprowski

2019

BioMed Eng OnLine

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Background Non-contact tonometers based on the method using air puff and Scheimpflug’s fast camera are one of the latest devices allowing the measurement of intraocular pressure and additional biomechanical parameters of the cornea. Biomechanical features significantly affect changes in intraocular pressure values, as well as their changes, may indicate the possibility of corneal ectasia. This work presents the latest and already known biomechanical parameters available in the new offered software. The authors focused on their practical application and the diagnostic credibility indicated in the literature. Discussion An overview of available literature indicates the importance of new dynamic corneal parameters. The latest parameters developed on the basis of biomechanics analysis of corneal deformation process, available in non-contact tonometers using Scheimpflug’s fast camera, are used in the evaluation of laser refractive surgery procedures, e.g. LASIK procedure. In addition, the assessment of changes in biomechanically corrected intraocular pressure confirms its independence from changes in the corneal biomechanics which may allow an intraocular pressure real assessment. The newly developed Corvis Biomechanical Index combined with the corneal tomography and topography assessment is an important aid in the classification of patients with keratoconus. Conclusion New parameters characterising corneal deformation, including Corvis Biomechanical Index and biomechanical compensated intraocular pressure, significantly extend the diagnostic capabilities of this device and may be helpful in assessing corneal diseases of the eye. Nevertheless, further research is needed to confirm their diagnostic pertinence.

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Section: Introductionmentioning

confidence: 99%

Novel dynamic corneal response parameters in a practice use: a critical review

Jędzierowska

Koprowski

2019

BioMed Eng OnLine

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“…Ocular Response Analyzer) for the detection of corneal biomechanics rely on large magnitude (millimeter-scale) global deformations of the eye [10], which causes nonlinear corneal response to the mechanical stimulation, leading to inaccurate measurement [11]. Also, the lack of depth-resolved detection limits the clinical usefulness of these techniques.…”

Section: Introductionmentioning

confidence: 99%

Noncontact depth-resolved micro-scale optical coherence elastography of the cornea

Wang

Larin

2014

Biomed. Opt. Express

155

129

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High-resolution elastographic assessment of the cornea can greatly assist clinical diagnosis and treatment of various ocular diseases. Here, we report on the first noncontact depth-resolved micro-scale optical coherence elastography of the cornea achieved using shear wave imaging optical coherence tomography (SWI-OCT) combined with the spectral analysis of the corneal Lamb wave propagation. This imaging method relies on a focused air-puff device to load the cornea with highly-localized lowpressure short-duration air stream and applies phase-resolved OCT detection to capture the low-amplitude deformation with nano-scale sensitivity. The SWI-OCT system is used here to image the corneal Lamb wave propagation with the frame rate the same as the OCT A-line acquisition speed. Based on the spectral analysis of the corneal temporal deformation profiles, the phase velocity of the Lamb wave is obtained at different depths for the major frequency components, which shows the depthwise distribution of the corneal stiffness related to its structural features. Our pilot experiments on ex vivo rabbit eyes demonstrate the feasibility of this method in depth-resolved micro-scale elastography of the cornea. The assessment of the Lamb wave dispersion is also presented, suggesting the potential for the quantitative measurement of corneal viscoelasticity. 3026-3031 (2007). 3. L. T. Nordan, "Keratoconus: diagnosis and treatment," Int. Ophthalmol. Clin. 37(1), 51-63 (1997). 4. C. Edmund, "Corneal elasticity and ocular rigidity in normal and keratoconic eyes," Acta Ophthalmol. (Copenh.) 66(2), 134-140 (1988 Biol. 93(1-3), 176-191 (2007). 17. G. Scarcelli and S. H. Yun, "Confocal Brillouin microscopy for three-dimensional mechanical imaging," Nat. ©2014 Optical Society of AmericaPhotonics 2(1), 39-43 (2008). 18. J. Schmitt, "OCT elastography: imaging microscopic deformation and strain of tissue," Opt. Express 3(6), 199-211 (1998). 19. G. Scarcelli and S. H. Yun, "In vivo Brillouin optical microscopy of the human eye," Opt. Express 20(8), 9197-9202 (2012). 20. G. Scarcelli, R. Pineda, and S. H. Yun, "Brillouin optical microscopy for corneal biomechanics," Invest.Ophthalmol. Vis. Sci. 53(1), 185-190 (2012). 21. G. Scarcelli, S. Kling, E. Quijano, R. Pineda, S. Marcos, and S. H. Yun, "Brillouin microscopy of collagen crosslinking: noncontact depth-dependent analysis of corneal elastic modulus," Invest. Ophthalmol. Vis. Sci.

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“…The obtained measurement results | n bl ( i ) − n br ( i )| ( Figure 4(d) ) confirm the cutoff vibration change of 0.2, 0.3 mm. The locations of points n bl and n br are also shown on the 3D reconstruction, in Figure 5 , which can be performed by using basic data concerning biomechanics of the cornea (mainly viscoelasticity) and its possible deformations [ 42 , 44 , 61 ].…”

Section: Methodsmentioning

confidence: 99%

Corneal Vibrations during Intraocular Pressure Measurement with an Air-Puff Method

Koprowski

Wilczyński

2018

Journal of Healthcare Engineering

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Introduction The paper presents a commentary on the method of analysis of corneal vibrations occurring during eye pressure measurements with air-puff tonometers, for example, Corvis. The presented definition and measurement method allow for the analysis of image sequences of eye responses—cornea deformation. In particular, the outer corneal contour and sclera fragments are analysed, and 3D reconstruction is performed. Methods On this basis, well-known parameters such as eyeball reaction or corneal response are determined. The next steps of analysis allow for automatic and reproducible separation of four different corneal vibrations. These vibrations are associated with (1) the location of the maximum of cornea deformation; (2) the cutoff area measured in relation to the cornea in a steady state; (3) the maximum of peaks occurring between applanations; and (4) the other characteristic points of the corneal contour. Results The results obtained enable (1) automatic determination of the amplitude of vibrations; (2) determination of the frequency of vibrations; and (3) determination of the correlation between the selected types of vibrations. Conclusions These are diagnostic features that can be directly applied clinically for new and archived data.

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Overview of the Ocular Biomechanical Properties Measured by the Ocular Response Analyzer and the Corvis ST

Cited by 8 publications

References 28 publications

Novel dynamic corneal response parameters in a practice use: a critical review

Novel dynamic corneal response parameters in a practice use: a critical review

Noncontact depth-resolved micro-scale optical coherence elastography of the cornea

Corneal Vibrations during Intraocular Pressure Measurement with an Air-Puff Method

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