  Understanding corneal stiffness is valuable for improving refractive surgery,
detecting corneal abnormalities, and assessing intraocular pressure. However,
accurately measuring the elastic properties, particularly the tensile and shear
moduli that govern mechanical deformation, has been challenging. To tackle this
issue, we have developed guided-wave optical coherence elastography that can
simultaneously excite and analyze symmetric (S0) and anti-symmetric (A0)
elastic waves in the cornea at frequencies around 10 kHz and allows us to
extract tensile and shear properties from measured wave dispersion curves. By
applying acoustoelastic theory that incorporates corneal tension and a
nonlinear constitutive tissue model, we verified the technique using elastomer
phantoms and ex vivo porcine corneas and investigated the dependence on
intraocular pressure. For two healthy human subjects, we measured a mean
tensile modulus of 3.6 MPa and a mean shear modulus of 76 kPa in vivo with
estimated errors of < 4%. This technique shows promise for the quantitative
biomechanical assessment of the cornea in a clinical setting.
