High myopes have lower normalised corneal tangent moduli (less ‘stiff’ corneas) than low myopes

Hon, Ying; Chen, Guo Zhen; Lu, Shuhao; Lam, David Chuen Chun; Lam, Andrew K. C.

doi:10.1111/opo.12335

Cited by 30 publications

(31 citation statements)

References 46 publications

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“…Previous works showed that subjects with high myopia had lower normalized corneal tangent moduli than subjects with low myopia had [ 25 – 27 ]. In addition, the cut pattern of the lenticule is different between pure spherical correction and those with sphere and cylinder correction; it could impact the results.…”

Section: Discussionmentioning

confidence: 99%

Preliminary Investigation of the Mechanical Anisotropy of the Normal Human Corneal Stroma

Xue

Xiang

Shen

et al. 2018

Journal of Ophthalmology

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Purpose To investigate the anisotropic characteristics of the normal human corneal stroma using fresh corneal tissue. Methods Sixty-four corneal specimens extracted from stromal lenticules were included in this study. The specimens were cut in the temporal-nasal (horizontal) or superior-inferior (vertical) direction. Strip specimens were subjected to uniaxial tensile testing. The tensile properties of the specimens were measured and compared in the two directions. Results The low-strain tangent modulus was statistically significantly greater in the vertical direction than in the horizontal direction (1.32 ± 0.50 MPa vs 1.17 ± 0.43 MPa; P=0.035), as was the high-strain tangent modulus (51.26 ± 8.23 MPa vs 43.59 ± 7.96 MPa; P ≤ 0.001). The elastic modulus in the vertical direction was also higher than that in horizontal direction at stresses of 0.01, 0.02, and 0.03 MPa, but not statistically significant; so, P=0.338, 0.373, and 0.417, respectively. Conclusions The biomechanical behavior in normal human corneal stroma tissue is slightly stiffer in the vertical direction than in the horizontal direction. This information may aid our understanding of the biomechanical properties of the cornea and related diseases.

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Section: Discussionmentioning

confidence: 99%

Preliminary Investigation of the Mechanical Anisotropy of the Normal Human Corneal Stroma

Xue

Xiang

Shen

et al. 2018

Journal of Ophthalmology

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“…A large number of clinical studies have found that CH and CRF are lower significantly in patients with myopia [ 28 ] and keratoconus [ 29 ] than normal cornea. Our results have showed a significant decrease at the stage of about 7 months of age, which indicates that corneal biomechanical properties were in the process of varying obviously at this stage.…”

Section: Discussionmentioning

confidence: 99%

“…If both the ORA parameters-age relations and the corneal biomechanical properties-age relations had been understood comprehensively, it is possible to study the biomechanical interpretations of CH and CRF by combining these two relationships. Besides, comparison of the ORA parameters-age relations and the corneal biomechanical properties-age relations will contribute to understanding the characteristic of CH and CRF in keratoconus patients and patients after refractive surgery, because the development of the keratoconus and the individualized design of corneal refractive surgery are closely related to corneal biomechanical properties [ 28 , 29 ]. Following this idea, we need to pay more attention to the biomechanical properties-age relations since there have been a number of results on ORA parameters-age relations and the age of the subjects ranged from 4 years to 91 years [ 4 , 16 – 23 ].…”

Section: Introductionmentioning

confidence: 99%

Age-Related Variations of Rabbit Corneal Geometrical and Clinical Biomechanical Parameters

Zhang

Xiao

Cao

et al. 2017

BioMed Research International

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Purpose To study the variations in corneal clinical biomechanical parameters (CCBP) and corneal geometrical parameters of rabbit in relation to age. Methods Rabbits aged 3, 7, 12, 18, and 24 months were enrolled. Each eye of the rabbits was tested with Ocular Response Analyzer (ORA), Optical Coherence Tomography (OCT), and Pachymeter to obtain the intraocular pressure (IOP): Goldmann-correlated IOP (IOPg) and Corneal Compensated Intraocular Pressure (IOPcc); CCBP: Corneal Hysteresis (CH) and Corneal Resistance Factor (CRF); corneal geometric parameters: corneal curvature radius (CCR) and central corneal thickness (CCT). Results The IOP of the rabbits changes slightly from 3 to 7 months of age, while it significantly decreases from 7 to 18 months of age and increases from 18 to 24 months of age; CH and CRF decrease with the increase of age; CCT increases from 7 to 18 months and decreases from 3 to 7 months of age and from 18 to 24 months of age; CCR presents an upward trend from 3 to 18 months and a significant decrease between 18 and 24 months of age. Conclusion CH and CRF are negatively correlated with age. CCT and CCR are positively correlated with age.

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“…The biomechanical behaviour of the cornea may be particularly relevant in clinical practice, as the cornea may be able to be considered as a surrogate for what might be happening elsewhere in the eye [3]. Corneal biomechanics have been reported to be altered in myopic patients, and with the degree of myopia [4], be combined with baseline age to predict the rate of axial elongation in myopic children [5], be altered in diabetic patients [6], in patients using topical prostaglandins [7] and patients with keratoconus [8] and as a sensitive marker of the ocular activity of collagen vascular diseases [9]. As a result, the study of corneal biomechanics has emerged as a very hot topic for research in ophthalmology [10].…”

Section: Introductionmentioning

confidence: 99%

A clinical method for estimating the modulus of elasticity of the human cornea in vivo

Pye

2020

PLoS ONE

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Background To develop a method, using current clinical instrumentation, to estimate the Young's modulus of the human cornea in vivo. Methods Central corneal curvature (CCC), central corneal thickness(CCT), intraocular pressure (IOP) was measured with the Goldmann tonometer (IOPG) and the Pascal Dynamic Corneal Tonometer(PDCT) in one eye of 100 normal young human subjects (21.07 ± 2.94 years) in vivo. The Orssengo and Pye algorithm was used to calculate the Young's modulus of the corneas of these subjects. Results The Young's modulus(E) of the corneas of the subjects using the PDCT and IOPG results (Ecalc) was 0.25 ± 0.10MPa, and without the PDCT results (Eiopg) was 0.29 ± 0.06MPa. The difference in these results is due to the difference in tonometry results between the two instruments, as the mean PDCT result for the subjects was 16.89 ± 2.49mmHg and the IOPG result 15.06 ± 2.71mmHg. E was affected by the CCC of the subjects but more particularly by the CCT and IOP measurements. Corneal stiffness results are also presented. Conclusion Two methods have been developed to estimate the Young's modulus of the human cornea in vivo using current clinical instrumentation. One method (Ecalc) is applicable to the general corneal condition, and Eiopg to the normal cornea, and these results can be used to calculate corneal stiffness.

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High myopes have lower normalised corneal tangent moduli (less ‘stiff’ corneas) than low myopes

Cited by 30 publications

References 46 publications

Preliminary Investigation of the Mechanical Anisotropy of the Normal Human Corneal Stroma

Preliminary Investigation of the Mechanical Anisotropy of the Normal Human Corneal Stroma

Age-Related Variations of Rabbit Corneal Geometrical and Clinical Biomechanical Parameters

A clinical method for estimating the modulus of elasticity of the human cornea in vivo

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