Comparative study of corneal tangent elastic modulus measurement using corneal indentation device

Ko, Match Wai Lun; Leung, Leo K.K.; Lam, David Chuen Chun

doi:10.1016/j.medengphy.2014.06.003

Cited by 17 publications

(15 citation statements)

References 37 publications

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“…The CID demonstrated very good agreement with a high prevision universal testing machine in measuring the tangent elastic modulus . Although we demonstrated good repeatability of the corneal indentation device in normal healthy corneas, additional studies are required.…”

Section: Discussionmentioning

confidence: 62%

“…11 Compared with its earlier prototype, the indenter in the current study was smaller (2 mm diameter) than the prototype (5 mm diameter). Ko et al 12 validated this device using a 2 mm indenter because a bigger indenter could create eye dislocation during indentation. Potentially a smaller indenter should be more comfortable to the subjects.…”

Section: Discussionmentioning

confidence: 99%

“…Corneal stiffness ( S ¦ IOP ) was calculated when the displacement (δ) was greater than

r_{o}^{2} / 2 R

, where r o is the radius of the circular contact area (1 mm in this case) and R is the mean K . The corneal tangent elastic modulus ( E ¦ IOP ) was calculated according to Equation ,

X X X X X X X X X X X X X X X X X X X X X X X X

where t is CCT, v is the Poisson's ration of the cornea ( v ≈ 0.5), and a is a geometry constant . The value of a depends on μ which can be calculated by Equation ,

\begin{matrix} μ = ro {(][, \frac{12 (1 - {italicν}^{2})}{{(R - \frac{t}{2})}^{2} t^{2}})}^{1 / 4} \end{matrix}

…”

Section: Methodsmentioning

confidence: 99%

“…The corneal tangent elastic modulus was calculated, and the device was tested in a silicone corneal model, porcine eyes ( ex vivo ), and rabbit eyes ( in vivo ) . The device was further compared with a high precision universal testing machine . Leung et al .…”

Section: Introductionmentioning

confidence: 99%

“…11 The device was further compared with a high precision universal testing machine. 12 Leung et al 13 demonstrated the feasibility of this device in measuring the corneal modulus in a small group of glaucoma patients.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Repeatability of a novel corneal indentation device for corneal biomechanical measurement

Lam

Hon

Leung

et al. 2015

Ophthalmic Physiologic Optic

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show abstract

Section: Discussionmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

“…Corneal stiffness ( S ¦ IOP ) was calculated when the displacement (δ) was greater than

r_{o}^{2} / 2 R

, where r o is the radius of the circular contact area (1 mm in this case) and R is the mean K . The corneal tangent elastic modulus ( E ¦ IOP ) was calculated according to Equation ,

X X X X X X X X X X X X X X X X X X X X X X X X

where t is CCT, v is the Poisson's ration of the cornea ( v ≈ 0.5), and a is a geometry constant . The value of a depends on μ which can be calculated by Equation ,

\begin{matrix} μ = ro {(][, \frac{12 (1 - {italicν}^{2})}{{(R - \frac{t}{2})}^{2} t^{2}})}^{1 / 4} \end{matrix}

…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Repeatability of a novel corneal indentation device for corneal biomechanical measurement

Lam

Hon

Leung

et al. 2015

Ophthalmic Physiologic Optic

View full text Add to dashboard Cite

show abstract

Finite element method for estimation of applanation force and to study the influence of intraocular pressure of eye on tonometry

et al. 2022

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Purpose Discover the associations of force of applanation on the eye with the plunging depth of the cornea and quantify them. The results will be utilized as the feedback parameter in the new prototype development of eye care instruments as additional force may damage the internal structure of the eye or may result in erroneous output. Method A finite element-based eye model is designed utilizing the actual dimensions of the human eye. A standardized tonometer is designed and the simulation is carried out at predetermined deformation of the cornea to find the force of applanation on the cornea during tonometry. Adding on, the influence of IOP during tonometry is analyzed for a range of plunging depths of the cornea. Results The graphical results inferred the linear relation between the force of applanation with the deformation of the cornea and the results are quantified. The resulting deformation and stress plot of FEM based simulation approach is analyzed and observations regarding deformations and stress are made. Conclusion The human eye is successfully developed and also computed force on the cornea during tonometry is validated. The inference drawn from the deformation plot and stress plot is that the junction of cornea–sclera along with cornea-tonometer periphery undergo maximum deformation and experiences the highest stress compared to other areas of the eye while during tonometry.

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Corneal Stiffness and Modulus of Normal-Tension Glaucoma in Chinese

Xu¹,

Ye²,

Chen³

et al. 2022

American Journal of Ophthalmology

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Comparative study of corneal tangent elastic modulus measurement using corneal indentation device

Cited by 17 publications

References 37 publications

Repeatability of a novel corneal indentation device for corneal biomechanical measurement

Repeatability of a novel corneal indentation device for corneal biomechanical measurement

Finite element method for estimation of applanation force and to study the influence of intraocular pressure of eye on tonometry

Corneal Stiffness and Modulus of Normal-Tension Glaucoma in Chinese

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