In vivo high-resolution mapping of the elastic moduli and tensile stress in the human cornea

ABSTRACT The mechanical balance between the elastic properties and tension in the cornea plays a critical role in normal vision, refractive corrective surgery, glaucoma screening, and the management of keratoconus. Several experimental and commercial instruments are available, and they have provided clinical data that suggest the potential values of biomechanical analysis. However, these devices offer limited quantitative resolution and cannot characterize corneal elastic properties that are highly anisotropic, nonlinear, and nonuniform. The overarching goal of this project is to advance optical coherence elastography (OCE) and use this technology to measure the mechanical parameters in human corneas with unprecedented details. Built on strong preliminary data, the new OCE harnesses extensional and flexural elastic waves guided along the cornea and determines tensile modulus and shear modulus, as well as tension, from the profiles and velocities of the waves. The first specific aim will develop wideband OCE using porcine and human cadaver eyes ex vivo. Algorithms to quantify elastic moduli and tension with high precision and resolution will be verified. The second specific aim will apply wideband OCE to obtain detailed mechanical data from human corneas in vivo. The study will involve healthy subjects across the lifespan, ocular hypertension patients, keratoconus patients, and subjects undergoing refractive surgeries. The potential impact of this project is immense, as the expected data will improve our understanding of corneal biomechanics in relation to the various natural, pathological, and interventional processes, and the technological advance may lead to a new clinical tool that can improve the diagnosis and treatment of keratoconus, the accuracy of tonometry, and the safety and visual outcome of refractive surgery.