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Subjects:

Research Funding:

This study was supported, in part, by National Institute of Health grants 2R01EY022362, 1R01HL120140, and U54HG006348, and by DOD CDMRP grant PR150338.

Keywords:

  • Science & Technology
  • Technology
  • Life Sciences & Biomedicine
  • Engineering, Biomedical
  • Radiology, Nuclear Medicine & Medical Imaging
  • Engineering
  • elastography
  • crystalline lens
  • acoustic radiation force
  • elastic wave
  • intraocular pressure
  • ACOUSTIC-RADIATION-FORCE
  • OPTIC-NERVE HEAD
  • EX-VIVO BOVINE
  • IN-VIVO
  • TRANSIENT ELASTOGRAPHY
  • MECHANICAL-PROPERTIES
  • VISCOELASTIC MEDIUM
  • SHEAR
  • PRESBYOPIA
  • SPEED

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

Tools:

Journal Title:

Physics in Medicine and Biology

Volume:

Volume 62, Number 3

Publisher:

, Pages N45-N57

Type of Work:

Article | Post-print: After Peer Review

Abstract:

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−1to 6.27 ± 0.75 m s−1as 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−1and 2.03 ± 0.46 m s−1, 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.

Copyright information:

© 2017 Institute of Physics and Engineering in Medicine.

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