Estimation of the biomechanical properties of ex-vivo porcine cornea and lens using air-coupled ultrasonic optical coherence elastography

The biomechanical properties of ocular tissues are critical for their function and can be significantly altered in various diseases such as keratoconus or cataract. The simultaneous assessment of cornea and crystalline lens stiffness can provide a comprehensive understanding of the biomechanical changes in these tissues in one assessment, reducing eye exposure and patient discomfort. This work demonstrates a completely contact-free characterization of the biomechanical properties of the lens and cornea simultaneously using an air-coupled ultrasonic (ACUS) transducer with optical coherence elastography (OCE). An unfocused 40 kHz ACUS transducer was used to induce elastic waves in the eye globe, which were imaged with a phase-sensitive OCT (PhS-OCT) system. OCE measurements were performed in ex vivo porcine eyes at various intraocular pressures (IOP), from 10 mmHg to 40 mmHg in 5 mmHg increments. The unfocused ACUS transducer generated mechanical waves at the limbus that traveled through the cornea and crystalline lens. The results showed differences in wave speed propagation in the cornea from 10 mmHg (3.16 m/s ± 0.65 m/s) to 40 mmHg (12.12 m/s ± 0.99 m/s) and the crystalline lens from 10 mmHg (2.75 m/s ± 0.22 m/s) to 40 mmHg (6.33 m/s ± 1.36 m/s). This method could be useful for a more comprehensive characterization of the mechanical properties of the major components of the ocular anterior segment in one measurement.