Finite element modelling of cornea mechanics: a review

Nejad, Talisa Mohammad; Foster, Craig D.; Gongal, Dipika

doi:10.5935/0004-2749.20140016

Cited by 48 publications

(33 citation statements)

References 55 publications

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“…Moreover, within each lamella, the collagen fibers run parallel to each other, but the alignment direction can vary from one lamella to another. Since the collagen fibers are the stiffest component of the cornea’s structure, the orientation distribution of these fibrils largely governs the mechanical properties of the cornea and leads them to be anisotropic [43, 44]. Future study will develop a structure-based constitutive model incorporating the orientation distribution of collagen fibers in different lamella in the cornea to characterize its dynamic mechanical response to the changes in IOP.…”

Section: Disuccsionmentioning

confidence: 99%

Noninvasive measurement of wave speed of porcine cornea in ex vivo porcine eyes for various intraocular pressures

2017

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The objective of this study was to extend an ultrasound surface wave elastography (USWE) technique for noninvasive measurement of ocular tissue elastic properties. In particular, we aim to establish the relationship between the wave speed of cornea and the intraocular pressure (IOP). Normal ranges of IOP are between 12 and 22 mmHg. Ex vivo porcine eye balls were used in this research. The porcine eye ball was supported by the gelatin phantom in a testing container. Some water was pour into the container for the ultrasound measurement. A local harmonic vibration was generated on the side of the eye ball. An ultrasound probe was used to measure the wave propagation in the cornea noninvasively. A 25 gauge butterfly needle was inserted into the vitreous humor of the eye ball under the ultrasound imaging guidance. The needle was connected to a syringe. The IOP was obtained by the water height difference between the water level in the syringe and the water level in the testing container. The IOP was adjusted between 5 mmHg and 30 mmHg with a 5 mmHg interval. The wave speed was measured at each IOP for three frequencies of 100, 150 and 200 Hz. Finite element method (FEM) was used to simulate the wave propagation in the corneal according to our experimental setup. A linear viscoelastic FEM model was used to compare the experimental data. Both the experiments and the FEM analyses showed that the wave speed of cornea increased with IOP.

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Section: Disuccsionmentioning

confidence: 99%

Noninvasive measurement of wave speed of porcine cornea in ex vivo porcine eyes for various intraocular pressures

2017

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“…The linear relationship of stress σ and elastic modulus E has been demonstrated by shell theory and prior experiments [14]. The matrix of the cornea is a viscoelastic and nearly incompressible material; this means that the density of the cornea should not vary during inflation [32]. According to the above discussion, IOP should have a direct effect on the acoustic impedance, which is the product of density and acoustic velocity.…”

Section: Discussionmentioning

confidence: 96%

Correlation of IOP with Corneal Acoustic Impedance in Porcine Eye Model

Zhang

et al. 2017

BioMed Research International

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Purpose The aim of this study is to correlate the intraocular pressure (IOP) change with the acoustic impedance of the cornea, in order to propose a noncontact and noninvasive method for IOP monitoring. Methods and Materials A highly focused transducer (frequency 47-MHz; bandwidth 62%) was made to measure the echo from the anterior and posterior surfaces of intact porcine eyes, respectively. A multilayered transmission and reflection model was used to calculate the acoustic impedance. The linear relationship between acoustic impedance and intraocular pressure was analyzed by statistical method. ResultDuring pressure elevation from 10 mm Hg to 50 mm Hg, the mean acoustic impedance of the posterior cornea increased from 1.5393 to 1.5698 MRayl, which showed a strong linear correlation (R = 0.9849; P = 0.0022). Meanwhile, the mean value of the anterior cornea increased from 1.5399 to 1.5519 MRayl, and a less significant correlation was observed (R = 0.7378; P = 0.0025). Conclusion This study revealed a linear correlation between intraocular pressure and acoustic impedance of the cornea, thus demonstrating a potentially important method to noninvasively measure the intraocular pressure in vivo.

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“…Mathematical models might prove to be useful in improving therapies such as UVA cross‐linking and limbal stem cell transplants to optimize locations of treatment and avoiding more damage due to the treatment . Lobo et al .…”

Section: Conclusion and Future Needsmentioning

confidence: 99%

Damaging Effects of Ultraviolet Radiation on the Cornea

Delic

Lyons

Girolamo

et al. 2017

Photochem & Photobiology

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The cornea sits at the anterior aspect of the eye and, like the skin, is highly exposed to ultraviolet radiation (UVR). The cornea blocks a significant proportion of UVB from reaching the posterior structures of the eye. However, UVA can penetrate the full thickness of the cornea, even reaching the anterior portion of the lens. Epidemiological data indicate that UVR is a contributing factor for a multitude of diseases of the cornea including pterygium, photokeratitis, climatic droplet keratopathy and ocular surface squamous neoplasia (OSSN), although the pathogenic mechanisms of each require further elucidation. UVR is a well‐known genotoxic agent, and its effects have been well characterized in organs such as the skin. However, we are only beginning to identify its effects on the cornea, such as the UVR signature C → T and CC → TT transversions identified by sequencing and increased proliferative and shedding rates in response to UVR exposure. Alarmingly, a single low‐dose exposure of UVR to the cornea is sufficient to elicit genetic, molecular and cellular changes, supporting the consideration of using protective measures, such as wearing sunglasses when outdoors. The aim of this review was to describe the adverse effects of UVR on the cornea.

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Finite element modelling of cornea mechanics: a review

Cited by 48 publications

References 55 publications

Noninvasive measurement of wave speed of porcine cornea in ex vivo porcine eyes for various intraocular pressures

Noninvasive measurement of wave speed of porcine cornea in ex vivo porcine eyes for various intraocular pressures

Correlation of IOP with Corneal Acoustic Impedance in Porcine Eye Model

Damaging Effects of Ultraviolet Radiation on the Cornea

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