  Objective: To compare non-contact acoustic micro-tapping optical coherence
elastography (AuT-OCE) with destructive mechanical tests to confirm corneal
elastic anisotropy.
  Design: Ex vivo, laboratory study with non-contact AuT-OCE followed by
mechanical rheometry and extensometry.
  Subjects: Inflated cornea of whole-globe porcine eyes.
  Methods: A non-contact transducer was used to launch mechanical waves in the
cornea that were imaged with phase-sensitive OCT at physiologically relevant
pressures. Reconstruction of both Young's modulus (E) and out-of-plane shear
modulus (G) in the cornea from experimental data was performed using a model of
a nearly incompressible transversally isotropic (NITI) medium. Samples were
then excised and parallel plate rheometry was performed to measure the shear
modulus G. Corneal samples were then subjected to strip extensomety to measure
the Young's modulus.
  Main Outcome Measures: Strong corneal anisotropy was confirmed with both
AuT-OCE and mechanical tests, with the Young's and shear moduli differing by
over an order of magnitude. These results show that AuT-OCE can quantify both
moduli with a non-contact, non-invasive, clinically translatable technique.
