  Purpose. To demonstrate accurate measurement of corneal elastic moduli in
vivo with non-contact and non-invasive optical coherence elastography. Methods.
Elastic properties (in-plane Young's modulus E and both in-plane, u, and
out-of-plane, G, shear moduli) of rabbit cornea were quantified in vivo using
non-contact dynamic Acoustic micro-Tapping Optical Coherence Elastography
(AuT-OCE). The IOP-dependence of measured mechanical properties was explored in
extracted whole globes following in vivo measurement. A nearly-incompressible
transverse isotropic (NITI) model was used to reconstruct moduli from AuT-OCE
data. Independently, cornea elastic moduli were also measured ex vivo with
traditional, destructive mechanical tests (tensile extensometry and shear
rheometry). Results. Our study demonstrates strong anisotropy of corneal
elasticity in rabbits. The in-plane Young's modulus, computer as E=3u, was in
the range of 20-44 MPa, whereas the out-of-plane shear modulus was in the range
of 34-261 kPa. Both pressure-dependent ex vivo OCE and destructive mechanical
tests performed on the same samples within an hour of euthanasia strongly
support the results of AuT-OCE measurements. Conclusions. Non-contact AuT-OCE
can non-invasively quantify cornea anisotropic elastic properties in vivo.
Translational Relevance. As OCT is broadly accepted in Ophthalmology, these
results suggest the potential for rapid translation of AuT-OCE into clinical
practice. In addition, AuT-OCE can likely improve diagnostic criteria of
ectatic corneal diseases, leading to early diagnosis, reduced complications,
customized surgical treatment, and personalized biomechanical models of the
eye.
