Spatial mapping of the biomechanical properties of rabbit cornea after cross-linking using optical coherence elastography

Keratoconus, a structural degeneration of the cornea, is often treated with UV-induced collagen cross-linking (CXL) to increase tissue resistance to further deformation and degeneration. Optimal treatment would be customized to the individual and consider pre-existing biomechanical properties as well as the effects induced by CXL. This requires the capability to noninvasively measure corneal mechanical properties. In this study, we demonstrate the use of phase-stabilized swept source optical coherence elastography (PhS-SSOCE) to assess the relaxation rate of a deformation which was induced by a focused air-pulse in tissue-mimicking gelatin phantoms of various concentration and partially cross-linked rabbit corneas. The temporal relaxation process was utilized to estimate the Young’s modulus from a newly developed model based elasticity reconstruction method. Due to the high spatial sensitivity of PhS-SSOCE, the deformation was only a few microns. The results show that the relaxation process was successfully used to differentiate the untreated (UT) and CXL region of the cornea. The results also indicate that the CXL regions had faster relaxation rates and greater Young’s moduli than the UT regions. Therefore, this method can be used to spatially assess the stiffness of the cornea. This non-contact and noninvasive measurement technique utilizes minimal force for excitation and can be potentially used to study the biomechanical properties of ocular and other sensitive tissues.