Optical coherence elastography measures the biomechanical properties of the ex vivo porcine cornea after LASIK.

Abstract

The biomechanical impact of refractive surgery has long been an area of investigation. Changes to the cornea structure cause alterations to its mechanical integrity, but few studies have examined its specific mechanical impact. To quantify how the biomechanical properties of the cornea are altered by laser assisted in situ keratomileusis (LASIK) using optical coherence elastography (OCE) in ex vivo porcine corneas. Three OCE techniques, wave-based air-coupled ultrasound (ACUS) OCE, heartbeat (Hb) OCE, and compression OCE were used to measure the mechanical properties of paired porcine corneas, where one eye of the pair was left untreated, and the fellow eye underwent LASIK. Changes in stiffness as a function of intraocular pressure (IOP) before and after LASIK were measured using each technique. ACUS-OCE showed that corneal stiffness changed as a function of IOP for both the untreated and the treated groups. The elastic wave speed after LASIK was lower than before LASIK. Hb-OCE and compression OCE showed regional changes in corneal strain after LASIK, where the absolute strain difference between the cornea anterior and posterior increased after LASIK. The results of this study suggest that LASIK may soften the cornea and that these changes are largely localized to the region where the surgery was performed.