April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
3D Strains in Porcine Superotemporal Posterior Sclera during Inflation
Author Affiliations & Notes
  • Benjamin Cruz Perez
    Department of Biomedical Engineering, Ohio State University, Columbus, OH
  • Hugh J Morris
    Department of Biomedical Engineering, Ohio State University, Columbus, OH
  • Hong Chen
    Department of Biomedical Engineering, Ohio State University, Columbus, OH
  • Xueliang Pan
    Center for Biostatistics, Ohio State University, Columbus, OH
  • Richard T Hart
    Department of Biomedical Engineering, Ohio State University, Columbus, OH
  • Jun Liu
    Department of Biomedical Engineering, Ohio State University, Columbus, OH
    Department of Ophthalmology, Ohio State University, Columbus, OH
  • Footnotes
    Commercial Relationships Benjamin Cruz Perez, None; Hugh Morris, None; Hong Chen, None; Xueliang Pan, None; Richard Hart, None; Jun Liu, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 4262. doi:
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    • Get Citation

      Benjamin Cruz Perez, Hugh J Morris, Hong Chen, Xueliang Pan, Richard T Hart, Jun Liu; 3D Strains in Porcine Superotemporal Posterior Sclera during Inflation. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4262.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To characterize the 3D strains of the porcine superotemporal posterior sclera during inflation using 3D high-resolution ultrasound speckle tracking.

 
Methods
 

Six porcine globes were tested within 72 hrs postmortem. The corneoscleral shell was mounted on a custom-made pressurization chamber and preconditioned by five cycles of inflation from 5 to 35 mmHg. After a 30 min equilibration at 15 mmHg, the shell was inflated to 17 mmHg and then 19 mmHg with a 7 min equilibration in between. The specimen was immersed in 0.9% saline solution during the tests. A volume of 5.5 mm long, 2 mm wide, and encompassing the full-thickness of the posterior superotemporal sclera was scanned using a 55-MHz ultrasound probe by stacking 2D scans with a 14 μm interval. 3D speckle tracking, validated in simulated radiofrequency data, was performed in the scanned volume using a modified cross-correlation algorithm (Tang & Liu, J Biomech Eng 2012, 134(9)). The full strain tensor was computed using a 3D least-squares strain estimator. Principal strains and volume ratios were computed. The scanned volume was further divided into two sub-regions of equal length (adjacent to ONH and about 2.5-mm away from ONH). The strains and volume ratios of these two regions were compared using paired t-tests.

 
Results
 

The principal strains and volume ratios for the overall scanned volume and the two sub-regions are summarized in Table 1. The region close to the ONH showed significantly larger compressive strains than the region farther from the ONH (p<0.001). In addition, as the pressure increased, the volume ratio decreased in the region close to the ONH (p=0.001) while increased in the region farther away (p=0.029).

 
Conclusions
 

Ultrasound speckle tracking was successfully implemented to measure the 3D deformation of the posterior sclera during inflation. Initial results suggested substantial negative strains (ε1) during IOP increase presumably due to radial compression. The regions immediately adjacent to the ONH appeared to have larger strains than the regions farther away from ONH. This technique may provide more complete experimental characterization of the posterior sclera and benefit the computational modeling efforts to elucidate the role of sclera in optic nerve damage.

     
Keywords: 708 sclera • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 568 intraocular pressure  
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