scholarly journals Influence of dextran solution and corneal collagen crosslinking on Corneal Biomechanical Parameters Evaluated by Corvis ST

2021 ◽  
Author(s):  
Xiao Qin ◽  
Lei Tian ◽  
Hui Zhang ◽  
Di Zhang ◽  
Li-Li Guo ◽  
...  
Keyword(s):  
Biomechanical Properties ◽  
Control Group ◽  
Corvis St ◽  
Collagen Crosslinking ◽  
Corneal Collagen Crosslinking ◽  
Biomechanical Parameters ◽  
Dextran Solution ◽  
Corneal Biomechanical Properties ◽  
Porcine Eyes ◽  
Corneal Collagen

Abstract Purpose: To analyze the influence of dextran solution and corneal collagen crosslinking (CXL) on corneal biomechanical parameters evaluated by Corneal Visualization Scheimpflug Technology (Corvis ST). Materials and Methods: Forty porcine eyes were included in this study. Twenty porcine eyes were soaked in dextran solution for 30 minutes (10 eyes in 2% dextran solution and 10 eyes in 20% dextran solution). CXL treatment was performed in 10 porcine eyes, the other 10 porcine eyes were regarded as a control group. Each eye was fixed on an experimental inflation platform to carry out Corvis measurements at different IOPs. Corneal biomechanical parameters were calculated based on Corvis measurement. Statistical analysis was used to analyze the influence of dextran solution and CXL on corneal biomechanical parameters based on Corvis parameters. Results: Corneal energy absorbed area (Aabsorbed) decreased after being soaked in dextran solution under IOP of 15 mmHg; Corneal elastic modulus (E) decreased after being soaked in 2% dextran solution and increased after being soaked in 20% dextran solution; SP-A1 increased after CXL. Conclusion: Both dextran solution and CXL can change corneal biomechanical properties; SP-A1 may be used as an effective parameter for the evaluation of CXL.

scholarly journals Compressional Optical Coherence Elastography of the Cornea

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 111
Author(s):  
Manmohan Singh ◽  
Achuth Nair ◽  
Salavat R. Aglyamov ◽  
Kirill V. Larin
Keyword(s):  
Rabbit Model ◽  
Biomechanical Properties ◽  
Clinical Applications ◽  
Optical Coherence ◽  
Collagen Crosslinking ◽  
Corneal Collagen Crosslinking ◽  
Corneal Biomechanical Properties ◽  
Corneal Collagen

Assessing the biomechanical properties of the cornea is crucial for detecting the onset and progression of eye diseases. In this work, we demonstrate the application of compression-based optical coherence elastography (OCE) to measure the biomechanical properties of the cornea under various conditions, including validation in an in situ rabbit model and a demonstration of feasibility for in vivo measurements. Our results show a stark increase in the stiffness of the corneas as IOP was increased. Moreover, UV-A/riboflavin corneal collagen crosslinking (CXL) also dramatically increased the stiffness of the corneas. The results were consistent across 4 different scenarios (whole CXL in situ, partial CXL in situ, whole CXL in vivo, and partial CXL in vivo), emphasizing the reliability of compression OCE to measure corneal biomechanical properties and its potential for clinical applications.

scholarly journals Corneal biomechanical properties in myopic eyes evaluated via Scheimpflug imaging

2020 ◽  
Author(s):  
A-Yong Yu ◽  
Hui Shao ◽  
Anpeng Pan ◽  
Qinmei Wang ◽  
Zixu Huang ◽  
...  
Keyword(s):  
Anterior Segment ◽  
Biomechanical Properties ◽  
Control Group ◽  
Spherical Equivalent ◽  
Corvis St ◽  
Scheimpflug Imaging ◽  
Biomechanical Parameters ◽  
Anterior Segment Parameters ◽  
Corneal Biomechanical Properties ◽  
Myopia Control

Abstract Background To investigate the biomechanical properties of the cornea in myopic eyes using corneal visualization scheimpflug technology (Corvis ST). The relationships between the biomechanical properties of the cornea and the degree of myopia were also investigated.Methods 265 eyes of 265 subjects were included. According to spherical equivalent (SE) in diopters (D), participants were divided into four groups: low myopia/control group (SE: -0.50 to -3.00D), moderate myopia group (SE: -3.00 to -6.00D), high myopia group (SE: -6.00 to -10.00D) and severe myopia group (SE greater than -10.00D). Axial length (AL), anterior segment parameters, and corneal biomechanical properties were obtained with the Lenstar LS900, Pentacam HR and Corvis ST, respectively. Results Mean (±SD) SE was -7.29±4.31D (range: -0.63 to -25.75D). Mean AL was 26.31±1.82mm (range: 21.87 to 31.94mm). Significant differences were detected within the four groups in terms of six corneal biomechanical parameters: deformation amplitude (DA), time from start until second applanation (A2-time), length of flattened cornea at the second applanation (A2-length), corneal velocity during the first and second applanation (A2-velocity), time from start to highest concavity (HC-time), and central curvature at highest concavity (HC radius). DA was positively correlated with AL ( r =0.16, P =0.009) and negatively correlated with SE ( r =-0.20, P =0.001). A2-time, A2-velocity, A2-length and HC-time were positively correlated with SE and negatively correlated with AL.Conclusions The alterations in corneal biomechanics may be associated with the degree of myopia. DA and A2-velocity may be useful corneal biomechanical indicators in patients with myopia.

scholarly journals Assessment of Corneal Biomechanical Properties by CorVis ST in Patients with Dry Eye and in Healthy Subjects

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Qin Long ◽  
Jingyi Wang ◽  
Xue Yang ◽  
Yumei Jin ◽  
Fengrong Ai ◽  
...  
Keyword(s):  
Correlation Analysis ◽  
Dry Eye ◽  
Healthy Subjects ◽  
Significant Negative Correlation ◽  
Biomechanical Properties ◽  
Control Group ◽  
Dry Eyes ◽  
Corvis St ◽  
Biomechanical Parameters ◽  
Corneal Biomechanical Properties

Purpose. To investigate corneal biomechanical properties in patients with dry eye and in healthy subjects using Corneal Visualization Scheimpflug Technology (CorVis ST).Methods.Biomechanical parameters were measured using CorVis ST in 28 eyes of 28 patients with dry eye (dry eye group) and 26 normal subjects (control group). The Schirmer I test value, tear film break-up time (TBUT), and corneal staining score (CSS) were recorded for each eye. Biomechanical properties were compared between the two groups and bivariate correlation analysis was used to assess the relationship between biomechanical parameters and dry eye signs.Results.Only one of the ten biomechanical parameters was significantly different between the two groups. Patients in the dry eye group had significantly lower highest concavity time (HC-time) (P=0.02) than the control group. Correlation analysis showed a significant negative correlation between HC-time and CSS with marginalPvalue (ρ=-0.39,P=0.04) in the dry eye group.Conclusions.The corneal biomechanical parameter of HC-time is reduced in dry eyes compared to normal eyes. There was also a very weak but significant negative correlation between HC-time and CSS in the dry eye group, indicating that ocular surface damage can give rise to a more compliant cornea in dry eyes.

Evaluation of changes in corneal biomechanics in eyes with keratectasia

2021 ◽  
pp. 179-187
Author(s):  
B.E. Malugin ◽  
◽  
E.G. Solodkova ◽  
S.V. Balalin ◽  
V.S. Kulikov ◽  
...  
Keyword(s):  
Corneal Thickness ◽  
Corneal Biomechanics ◽  
Corvis St ◽  
Collagen Crosslinking ◽  
The Third ◽  
Corneal Rigidity ◽  
Corneal Collagen Crosslinking ◽  
Early Features ◽  
Healthy Persons ◽  
Corneal Collagen

Purpose. To make a comparative analysis of topographic, tomographic and biomechanical values, measured by Pentacam HR and Corvis ST, in healthy multirefractive cohort versus patients with keratectasia of various severity. Material and methods. The prospective study comprised 237 patients aged from 18 to 47 years, subdivided into three groups. The first group included 174 healthy persons with various refraction (174 eyes). The second and the third group embraced 63 patients with keratoconus: 36 patients (36 eyes) with keratoconus of the I degree and 27 eyes with keratoconus of the II and III degrees. Besides the conventional comprehensive ocular examination the following studies were performed in all the patients: evaluation of topographic, tomographic and biomechanical corneal properties with application of Pentacam HR and Corvis ST (OCULUS Optikgerate GmbH; Wetzlar, Germany). Results. It was revealed that the following biomechanical values, assessed by means of Pentacam HR and Corvis ST, exhibited statistically significant changes (p<0,001) in all degrees of ketatoconus: a relative corneal thickness by Ambrosio, inverted radius of applanation curvature (IntRadius), DA Ratio Coefficient, values of corneal rigidity – SP-A 1 and SSI. Conclusion. The detected parameters may be applied as indicators, allowing to evaluate corneal biomechanics, to define early features of ectatic process, to assess effectiveness of the performed corneal collagen crosslinking and intralamellar keratoplasty with implantation of corneal segments. Key words: keratoconus, corneal biomechanics, pachymetry, index of pachymetric progression, corneal viscoelasticity.

Analysis of keratopographic and biomechanical corneal indicators with evaluation of the impact of diagnostic results on myopic refraction patient management tactics

2021 ◽  
pp. 196-199
Author(s):  
D.D. Sibakin ◽  
◽  
V.A. Breev ◽  
E.G. Solodkova ◽  
◽  
...  
Keyword(s):  
Patient Management ◽  
Screening Program ◽  
Clinical Stage ◽  
Biomechanical Properties ◽  
Corvis St ◽  
Stage Of Development ◽  
Biomechanical Parameters ◽  
The Impact ◽  
Biomechanical Measurements ◽  
Corneal Biomechanical Properties

Purpose. To analyse keratopographic and biomechanical corneal indicators with the diagnostic results assessment of the influence on the treatment tactics of myopic refraction patient. Materials and methods. Keratotopographic and biomechanical parameters of the cornea in a patient with mild myopia were evaluated. Results. The Belin/Ambrosio (Enchanced Ectasia Display) - BAD keratoconus screening program was used on Pentacam HR, which did not reveal corneal pathology. According to the results of CBI (Corvis biomechanical index) on Corvis ST (OD - 0.61, OS - 0.48), that was indicating poor corneal biomechanical properties and a high risk of keratectasia development. Conclusion. Ophthalmic examination, using The Corvis ST (Oculus, Germany) biomechanical measurements, makes possible to reveal with greater sensitivity subclinical signs of a keratectatic process at the pre-clinical stage of development. Key words: keratotopography, corneal biomechanics, keratoconus.

scholarly journals Corneal Biomechanical Assessment Using Corneal Visualization Scheimpflug Technology in Keratoconic and Normal Eyes

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Lei Tian ◽  
Yi-Fei Huang ◽  
Li-Qiang Wang ◽  
Hua Bai ◽  
Qun Wang ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Corneal Thickness ◽  
Area Under The Curve ◽  
Biomechanical Properties ◽  
Corvis St ◽  
Biomechanical Assessment ◽  
Deformation Amplitude ◽  
Biomechanical Parameters ◽  
And Control ◽  
Corneal Biomechanical Properties

Purpose. To compare the corneal biomechanical properties of keratoconic patients and age-matched controls using corneal visualization Scheimpflug technology (Corvis ST).Methods. Sixty keratoconic eyes from 47 keratoconus patients and 60 normal eyes from 60 controls were enrolled in this prospective study. Tomography and biomechanical parameters of all eyes were obtained with the Pentacam and Corvis ST, respectively. Intraocular pressure was measured using a Goldmann applanation tonometer.Results.The tomography and biomechanical parameters of the keratoconic corneas were significantly different from those of the normal corneas except for the anterior chamber angle, first applanation length, the highest concavity time, and peak distance. The deformation amplitude was the best predictive parameter (area under the curve: 0.882), with a sensitivity of 81.7%, although there was a significant overlap between keratoconic and normal corneas that ranged from 1.0 to 1.4 mm. In both the keratoconus and control groups, the deformation amplitude was negatively correlated with intraocular pressure, central corneal thickness, and corneal volume at 3 and 5 mm.Conclusions. Corvis ST offers an alternative method for measuring corneal biomechanical properties. The possibility of classifying keratoconus based on deformation amplitude deserves clinical attention.

scholarly journals Corneal biomechanical properties in myopic eyes evaluated via Scheimpflug imaging

2020 ◽  
Author(s):  
A-Yong Yu ◽  
Hui Shao ◽  
Anpeng Pan ◽  
Qinmei Wang ◽  
Zixu Huang ◽  
...  
Keyword(s):  
Axial Length ◽  
High Myopia ◽  
Anterior Segment ◽  
Biomechanical Properties ◽  
Corvis St ◽  
Negatively Associated ◽  
Scheimpflug Imaging ◽  
Biomechanical Parameters ◽  
Corneal Biomechanical Properties ◽  
Myopia Control

Abstract Background: To investigate the biomechanical properties of the cornea in myopic eyes using corneal visualization scheimpflug technology (Corvis ST). The relationships between the biomechanical properties of the cornea and the degree of myopia were also investigated.Methods: 265 eyes of 265 subjects were included. Based on spherical equivalent (SE) in diopters (D), participants were divided into four groups: low myopia/control (SE: -0.50 to -3.00D), moderate myopia (SE: -3.00 to -6.00D), high myopia (SE: -6.00 to -10.00D) and severe myopia (SE greater than -10.00D). Axial length (AL), anterior segment parameters, and corneal biomechanical properties were obtained with the Lenstar LS900, Pentacam HR and Corvis ST, respectively.Results: Mean (±SD) SE was -7.29±4.31D (range: -0.63 to -25.75D). Mean AL was 26.31±1.82mm (range: 21.87 to 31.94mm). Significant differences were detected within the four groups in terms of six corneal biomechanical parameters: deformation amplitude (DA), time from start until second applanation (A2-time), length of flattened cornea at the second applanation (A2-length), corneal velocity during the first and second applanation (A2-velocity), time from start to highest concavity (HC-time), and central curvature at highest concavity (HC radius). AL was positively associated with DA whereas negatively associated with A1-velocity and A2-length. SE was positively associated with A2-time, HC-time and A2-velocity, whereas negatively associated with DA. IOP was positively associated with four corneal biomechanical parameters and negatively associated with three parameters.Conclusions: Eyes with severe myopia showed greater DA, lesser A2 time, HC time, and faster A2-velocity compared to low to high myopia. This suggests the cornea becomes weaker and more deformable with elongation of axial length with corresponding increases in myopia. DA, A2-time and A2-velocity could be useful corneal biomechanical indicators in patients with myopia.

scholarly journals Association between Iris Biological Features and Corneal Biomechanics in Myopic Eyes

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Lin Fu ◽  
Qi Dai ◽  
Pengzhi Zhu ◽  
Xu Jia ◽  
Fangjun Bao ◽  
...  
Keyword(s):  
Biomechanical Properties ◽  
Corneal Biomechanics ◽  
Detection Methods ◽  
Arc Length ◽  
Linear Regression Models ◽  
Corvis St ◽  
Surface Features ◽  
Biological Features ◽  
Biomechanical Parameters ◽  
Corneal Biomechanical Properties

Purpose. Iris biological features such as surface features and profile characteristics reflected the development of iris stroma and microvessels. Iris vessels and microcirculation are still lack of effective detection methods, and we can directly observe only the iris surface biological characteristics. This cross-sectional study evaluated the association between iris surface biological features and corneal biomechanics in young adults with myopia. Methods. We recruited 152 patients with myopia aged ≥18 years, from the Eye Hospital of Wenzhou Medical University, who had complete Corneal Visualization Scheimpflug Technology (Corvis ST) data and graded iris surface features. Iris surface features included crypts, furrows, and color measured from digital slit lamp images. The biomechanical properties of the cornea were assessed using Corvis ST. Only 1 eye of each participant was randomly selected for analysis. Associations between the iris surface features and corneal biomechanics were analyzed using linear regression models. The grade of iris crypts, furrows, and color and corneal biomechanical parameters measured with Corvis ST was the main outcome measures. Results. The iris crypts were significantly associated with deflection amplitude at the first applanation (A1 DLA, β = 0.001 , P = 0.013 ), A1 delta arc length (A1 dArcL) ( β = − 0.001 , P = 0.01 ), maximum delta arc length (dArcLM) ( β = − 0.004 , P = 0.03 ), and stiffness at the first applanation (SP-A1) ( β = − 2.092 , P = 0.016 ). The iris furrows were only associated with integrated radius ( β = − 0.212 , P = 0.025 ). Iris color was found not related with corneal biomechanical parameters measured via Corvis ST. Conclusions. Iris surface features were associated with corneal biomechanical properties in myopic eyes; more iris crypts were associated with lower corneal stiffness while more extensive furrows were related with higher corneal stiffness. Iris crypts and furrows may provide useful information on corneal biomechanical properties in myopic eyes.

scholarly journals Corneal Biomechanical Properties in Myopic Eyes Measured by a Dynamic Scheimpflug Analyzer

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jingyi Wang ◽  
Ying Li ◽  
Yumei Jin ◽  
Xue Yang ◽  
Chan Zhao ◽  
...  
Keyword(s):  
Correlation Analysis ◽  
Axial Length ◽  
Biomechanical Properties ◽  
Spherical Equivalent ◽  
Corvis St ◽  
Deformation Amplitude ◽  
Bivariate Correlation ◽  
Biomechanical Parameters ◽  
The Relationship ◽  
Corneal Biomechanical Properties

Purpose. To evaluate the corneal biomechanical parameters in myopic and emmetropic eyes using Corneal Visualization Scheimpflug Technology (CorVis ST).Methods.103 myopic and emmetropic eyes of 103 patients were examined. Corneal biomechanical parameters, axial length, and mean keratometry were measured using CorVis ST, IOL Master, and topography, respectively. Corneal biomechanical properties were compared within four groups. Bivariate correlation analysis was used to assess the relationship between corneal biomechanical parameters and ocular characteristics.Results.Four of ten corneal biomechanical parameters, namely, deformation amplitude (DA), first- and second-applanation time (A1-time, A2-time), and radius at highest concavity (HC radius), were significantly different within the four groups (P<0.05). In correlation analysis, DA was positively correlated with axial length (r=0.20,P=0.04); A2-time was positively correlated with spherical equivalent (SE) (r=0.24,P=0.02); HC radius was positively correlated with SE (r=0.24,P=0.02) and was negatively correlated with mean keratometry (r=-0.20,P=0.046) and axial length (r=-0.21,P=0.03).Conclusions.The corneal refraction-related biomechanical alterations were associated with ocular characteristics. Highly myopic eyes exhibited longer DA and smaller HC radius than do moderately myopic eyes; the eyes with longer axial length tend to have less corneal stiffness and are easier to deform under stress.

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