The dynamic deformation of a layered viscoelastic medium under surface excitation

Aglyamov, Salavat R.; Wang, Shang; Karpiouk, Andrei; Li, Jiasong; Twa, Michael D.; Emelianov, Stanislav; Larin, Kirill V.

doi:10.1088/0031-9155/60/11/4295

Cited by 25 publications

(13 citation statements)

References 34 publications

(62 reference statements)

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“…In the previous investigations, lens stiffness was mostly involved as an age-related connection with presbyopia (Glasser et al , 2001; Heys et al , 2004; Wu et al , 2015; Pau and Kranz, 1991; Loupas et al , 1995; Aglyamov et al , 2015). Yoon et al (2013) measure the Young’s modulus an shear viscosity from extracted bovine and porcine lenses in mature (25–30 months old) and young (6 months old) ages using laser induced microbubbles.…”

Section: Discussionmentioning

confidence: 98%

“…In this paper, we assess the mechanical properties of the crystalline lens using ultrasound shear wave elasticity imaging and we believe it is the first time the speed of elastic waves in the crystalline lens ex vivo in response to IOP changes is measured. It should be noted that the elastic waves propagating in the crystalline lens are Rayleigh waves (i.e., surface waves) and, therefore, the elastic waves in the cornea and the lens are different types of elastic waves due to boundary conditions (Aglyamov et al , 2015; Nenadic et al , 2011). Therefore, in this paper, the waves generated in both cornea and lens (Lamb and Rayleigh waves in cornea and lens, respectively) are referred to as elastic waves and their speeds of elastic waves are compared as functions of IOP.…”

Section: Introductionmentioning

confidence: 99%

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The impact of intraocular pressure on elastic wave velocity estimates in the crystalline lens

et al. 2017

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Intraocular pressure (IOP) is believed to influence the mechanical properties of ocular tissues including cornea and sclera. The elastic properties of the crystalline lens have been mainly investigated with regard to presbyopia, the age-related loss of accommodation power of the eye. However, the relationship between the elastic properties of the lens and IOP remains to be established. The objective of this study is to measure the elastic wave velocity, which represents the mechanical properties of tissue, in the crystalline lens ex vivo in response to changes in IOP. The elastic wave velocities in the cornea and lens from seven enucleated bovine globe samples were estimated using ultrasound shear wave elasticity imaging. To generate and then image the elastic wave propagation, an ultrasound imaging system was used to transmit a 600 µs pushing pulse at 4.5 MHz center frequency and to acquire ultrasound tracking frames at 6 kHz frame rate. The pushing beams were separately applied to the cornea and lens. IOP in the eyeballs was varied from 5 to 50 mmHg. The results indicate that while the elastic wave velocity in the cornea increased from 0.96 ± 0.30 m/s to 6.27 ± 0.75 m/s as IOP was elevated from 5 to 50 mmHg, there were insignificant changes in the elastic wave velocity in the crystalline lens with the minimum and the maximum speeds of 1.44 ± 0.27 m/s and 2.03 ± 0.46 m/s, respectively. This study shows that ultrasound shear wave elasticity imaging can be used to assess the biomechanical properties of the crystalline lens noninvasively. Also, it was observed that the dependency of the crystalline lens stiffness on the IOP was significantly lower in comparison with that of cornea.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

The impact of intraocular pressure on elastic wave velocity estimates in the crystalline lens

et al. 2017

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“… 13 , 18 Although the OCE measurements were performed only on the lens surface, it is known that the surface wave is also sensitive to deep layers of the medium, depending on the wavelength of the elastic wave. 44 – 46 Though the scan width was greater than the width of the cold cataract, the width that we used to calculate group velocity was only

across the center of the apex of the lens, which means the group velocity measurements were from the region over the cataract. In our case, as seen in Fig.…”

Section: Discussionmentioning

confidence: 99%

Optical coherence elastography of cold cataract in porcine lens

Zhang

Singh

et al. 2019

J. Biomed. Opt.

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Cataract is one of the most prevalent causes of blindness around the world. Understanding the mechanisms of cataract development and progression is important for clinical diagnosis and treatment. Cold cataract has proven to be a robust model for cataract formation that can be easily controlled in the laboratory. There is evidence that the biomechanical properties of the lens can be significantly changed by cataract. Therefore, early detection of cataract, as well as evaluation of therapies, could be guided by characterization of lenticular biomechanical properties. In this work, we utilized optical coherence elastography (OCE) to monitor the changes in biomechanical properties of ex vivo porcine lenses during formation of cold cataract. Elastic waves were induced in the porcine lenses by a focused micro air-pulse while the lenses were cooled, and the elastic wave velocity was translated to Young's modulus of the lens. The results show an increase in the stiffness of the lens due to formation of the cold cataract (from 11.3 AE 3.4 to 21.8 AE 7.8 kPa). These results show a relation between lens opacity and stiffness and demonstrate that OCE can assess lenticular biomechanical properties and may be useful for detecting and potentially characterizing cataracts.

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“…It is well known that lens stiffness has a strong correlation with age [ 10 , 27 – 31 ]. Pau et al used a miniature dynamometer to measure the penetration resistance of the fine conical probe to different lens layers to investigate the relationship between human lens stiffness and age [ 1 ].…”

Section: Discussionmentioning

confidence: 99%

Noninvasive assessment of age-related stiffness of crystalline lenses in a rabbit model using ultrasound elastography

et al. 2018

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BackgroundThe pathological or physiological changes of a crystalline lens directly affect the eye accommodation and transmittance, and then they increase the risk of presbyopia and cataracts for people in the middle and old age groups. There is no universally accepted quantitative method to measure the lens' mechanical properties in vivo so far. This study aims to investigate the possibility of assessing the age-related stiffness change of crystalline lens by acoustic-radiation-force-based ultrasound elastography (ARF-USE) in a rabbit model in vivo.MethodsThere were 13 New Zealand white rabbits that were divided into four groups and fed normally until they were 60 (n = 4), 90 (n = 2), 120 (n = 4), and 150 (n = 3) days old, respectively. An ARF-USE platform was built based on the Verasonics™ Vantage 256 system. The shear waves were excited and traced in the lens by a linear ultrasound probe after a rabbit was anaesthetized.ResultsThe average group velocities were 1.38 ± 0.2 m/s, 2.06 ± 0.3 m/s, 2.07 ± 0.29 m/s, and 2.30 ± 0.28 m/s, respectively, for the four groups of rabbits. The results shows that the group velocity has a strong correlation with the day age (r = 0.84, p < 1 × 10−7) and the weight (r = 0.83, p < 1×10−7) of the rabbits while the maximum displacement has no correlations with the day age (r = 0.27, p > 0.1) and the weight (r = 0.32, p > 0.1).ConclusionThis study demonstrated that the group velocity measured by ARF-USE had a strong correlation with age-related stiffness in a rabbit model, suggesting that group velocity is a good biomarker to characterize the stiffness of a crystalline lens. This study also demonstrated the feasibility of using this USE technique to assess the mechanical properties of the lens in vivo for clinical or research purposes.

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The dynamic deformation of a layered viscoelastic medium under surface excitation

Cited by 25 publications

References 34 publications

The impact of intraocular pressure on elastic wave velocity estimates in the crystalline lens

The impact of intraocular pressure on elastic wave velocity estimates in the crystalline lens

Optical coherence elastography of cold cataract in porcine lens

Noninvasive assessment of age-related stiffness of crystalline lenses in a rabbit model using ultrasound elastography

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