Association between Iris Biological Features and Corneal Biomechanics in Myopic Eyes

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.

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Association of Iris Structural Measurements with Corneal Biomechanics in Myopic Eyes

Disease Markers ◽

10.1155/2021/2080962 ◽

2021 ◽

Vol 2021 ◽

pp. 1-6

Author(s):

Lin Fu ◽

Yufeng Ye ◽

Xu Jia ◽

Yunjie Zhang ◽

Xiaoyu Chen ◽

...

Keyword(s):

Young Adults ◽

Biomechanical Properties ◽

Corneal Biomechanics ◽

Linear Regression Models ◽

Swept Source ◽

Corvis St ◽

Sectional Parameters ◽

Medical University ◽

The Relationship ◽

Corneal Biomechanical Properties

Purpose. To evaluate the relationship between iris sectional parameters on swept-source optical coherence tomography (SS-OCT) with corneal biomechanics measured by Corneal Visualization Scheimpflug Technology (Corvis ST) in young adults with myopia. Methods. 117 patients with myopia aged ≥18 years were recruited from the Eye Hospital of Wenzhou Medical University, who had complete SS-OCT and Corvis ST data. Only the left eye of each participant was selected for analysis. Iris sectional parameters included iris thickness at 750 μm from the scleral spur (IT750), iris sectional area (I-area), and iris curvature (I-curv) measured from four quadrants. Associations between the iris parameters and corneal biomechanics were analyzed using linear regression models. Results. The mean age of the included young adults was 26.26 ± 6.62 years old with 44 males and 73 females. The iris parameters were different among the four quadrants. The nasal, temporal, and inferior quadrants of IT750, together with nasal and temporal quadrants of I-area, were correlated with corneal biomechanical parameters after being adjusted for age, gender, pupil diameter, and axial length. Thicker IT750 and larger I-area were related to a softer cornea. However, no association was found between I-curv and corneal biomechanics. Conclusions. Iris sectional parameters measured from SS-OCT images were associated with corneal biomechanical properties in myopic eyes. Thicker IT750 and larger I-area indicate a softer cornea. IT750 and I-area may provide useful information on corneal biomechanical properties in myopic eyes.

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

Modern technologies in ophtalmology ◽

10.25276/2312-4911-2021-2-196-199 ◽

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.

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

Journal of Ophthalmology ◽

10.1155/2014/147516 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 46

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.

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

10.21203/rs.3.rs-742842/v1 ◽

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.

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Corneal biomechanical properties in myopic eyes evaluated via Scheimpflug imaging

10.21203/rs.3.rs-18474/v2 ◽

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.

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

Journal of Ophthalmology ◽

10.1155/2015/161869 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 4

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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Corneal biomechanical properties in myopic eyes evaluated via Scheimpflug imaging

10.21203/rs.3.rs-18474/v1 ◽

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.

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

Journal of Ophthalmology ◽

10.1155/2015/380624 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7 ◽

Cited By ~ 5

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.

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Corneal Biomechanical Properties in Varying Severities of Myopia

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2020.595330 ◽

2021 ◽

Vol 8 ◽

Author(s):

Mohammad-Reza Sedaghat ◽

Hamed Momeni-Moghaddam ◽

Abbas Azimi ◽

Zohreh Fakhimi ◽

Mohammed Ziaei ◽

...

Keyword(s):

Axial Length ◽

Corneal Thickness ◽

Biomechanical Properties ◽

Cross Sectional Study ◽

Geometrical Parameters ◽

Cross Sectional ◽

Corvis St ◽

Multiple Parameters ◽

Inverse Radius ◽

Biomechanical Parameters

Purpose: To investigate corneal biomechanical response parameters in varying degrees of myopia and their correlation with corneal geometrical parameters and axial length.Methods: In this prospective cross-sectional study, 172 eyes of 172 subjects, the severity degree of myopia was categorized into mild, moderate, severe, and extreme myopia. Cycloplegic refraction, corneal tomography using Pentacam HR, corneal biomechanical assessment using Corvis ST and Ocular Response Analyser (ORA), and ocular biometry using IOLMaster 700 were performed for all subjects. A general linear model was used to compare biomechanical parameters in various degrees of myopia, while central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were considered as covariates. Multiple linear regression was used to investigate the relationship between corneal biomechanical parameters with spherical equivalent (SE), axial length (AXL), bIOP, mean keratometry (Mean KR), and CCT.Results: Corneal biomechanical parameters assessed by Corvis ST that showed significant differences among the groups were second applanation length (AL2, p = 0.035), highest concavity radius (HCR, p < 0.001), deformation amplitude (DA, p < 0.001), peak distance (PD, p = 0.022), integrated inverse radius (IR, p < 0.001) and DA ratio (DAR, p = 0.004), while there were no significant differences in the means of pressure-derived parameters of ORA between groups. Multiple regression analysis showed all parameters of Corvis ST have significant relationships with level of myopia (SE, AXL, Mean KR), except AL1 and AL2. Significant biomechanical parameters showed progressive reduction in corneal stiffness with increasing myopia (either with greater negative SE or greater AXL), independent of IOP and CCT. Also, corneal hysteresis (CH) or ability to dissipate energy from the ORA decreased with increasing level of myopia.Conclusions: Dynamic corneal response assessed by Corvis ST shows evidence of biomechanical changes consistent with decreasing stiffness with increasing levels of myopia in multiple parameters. The strongest correlations were with highest concavity parameters where the sclera influence is maximal.

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The changes of corneal biomechanical properties with long-term treatment of prostaglandin analogue measured by Corvis ST

10.21203/rs.3.rs-22280/v3 ◽

2020 ◽

Author(s):

Na Wu ◽

Yuhong Chen ◽

Yaping Yang ◽

Xinghuai Sun

Keyword(s):

Open Angle Glaucoma ◽

Corneal Thickness ◽

Biomechanical Properties ◽

Term Treatment ◽

Prostaglandin Analogue ◽

Corvis St ◽

Long Term Treatment ◽

Corneal Biomechanical Properties

Abstract Background: To investigate the corneal biomechanical changes in primary open angle glaucoma (POAG) patients treated with long-term prostaglandin analogue (PGA). Methods: 111 newly diagnosed POAG patients, including 43 high tension glaucoma (HTG) and 68 normal tension glaucoma (NTG), were measured by Corvis ST to obtain intraocular pressure (IOP), central corneal thickness (CCT) and corneal biomechanical parameters at baseline and at each follow-up visit after initiation of PGA treatment. The follow-up measurements were analyzed by the generalized estimate equation model with an exchangeable correlation structure. Restricted cubic spline was employed to estimate the dose-response relation between follow-up time and corneal biomechanics．Results: The mean follow-up time was 10.3 ± 7.02 months. Deformation amplitude (β=-0.0015, P=0.016), the first applanation velocity (AV1, β=-0.0004, P=0.00058) decreased and the first applanation time (AT1, β=0.0089, P<0.000001) increased statistically significantly with PGA therapy over time after adjusting for age, gender, axial length, corneal curvature, IOP and CCT. In addition, AT1 was lower (7.2950 ± 0.2707 in NTG and 7.5889 ± 0.2873 in HTG, P=0.00011) and AV1 was greater (0.1478 ± 0.0187 in NTG and 0.1314 ± 0.0191 in HTG, P=0.00002) in NTG than in HTG after adjusting for confounding factors.Conclusions: Chronic use of PGA probably influences the corneal biomechanical properties directly, which is to make cornea less deformable. Besides, corneas in NTG tended to be more deformable compared to those in HTG with long-term treatment of PGA.

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