In vivo assessment of corneal shear anisotropy using supersonic shear wave imaging
Résumé
The cornea is mainly composed of fibrillar collagen. The fibers organization ensures the cornea transparency and determines its biomechanics. Understanding these properties is a crucial issue in ophthalmology to improve the management of refractive surgery. Here, we propose Supersonic Shear Wave Imaging (SSI) for the in vivo assessment of the corneal elastic anisotropy. The tissue shear modulus can be retrieved from the speed of a shear wave propagating through the tissue. In the SSI technique, the shear wave is induced and tracked using an ultrafast (30000 frames/sec) ultrasonic scanner (Aixplorer, SuperSonic Imagine). We performed in vivo 3D scans on porcine eyes. Elasticity maps exhibited significantly higher shear wave speed along the horizontal meridian of the cornea (8.7 ± 0.3 m/s) than along the diagonal and vertical directions (6.6 ± 0.2 m/s). Ex vivo X-ray diffraction measurements [The Anat. Rec. 290, 1542-1550 (2007)] have shown that the collagen fibers have one preferential orientation in porcine corneas. The elasticity maps obtained in vivo using SSI are consistent with ex vivo results reported in literature, demonstrating the sensitivity of SSI to collagen fibers orientation.
Domaines
Acoustique [physics.class-ph]
Origine : Fichiers éditeurs autorisés sur une archive ouverte