A Quantitative Ultrasonic Spectroscopy Method for Noninvasive Determination of Corneal Biomechanical Properties

Abstract

Purpose.: To describe a quantitative ultrasonic spectroscopy technique for the noninvasive characterization of corneal biomechanical properties and to compare these measurements with established techniques in a porcine eye model. Methods.: An ultrasound system was constructed to accurately acquire acoustic reflections from corneas through a saline bath. Corneal properties (including thickness, density and aggregate modulus) were estimated from the measured reflection spectra based on wave propagation analysis. Twenty fresh porcine corneas were measured using the quantitative ultrasound method and other established techniques that can only be applied to dissected corneas. Results.: The ultrasonic measurements of corneal thickness and aggregate modulus were significantly correlated with the measurements of established techniques (Pearson's correlation = 0.99 and 0.61; P < 0.005), and good sample-to-sample consistency was achieved. The measurement of corneal density agreed well in terms of mean and range, but the correlation did not achieve statistical significance (Pearson's correlation = 0.41; P = 0.07). Conclusions.: The ultrasonically measured corneal biomechanical properties agreed well with the measurements obtained by using established techniques, validating the accuracy of the ultrasound method. Quantitative ultrasound spectroscopy may provide a noninvasive approach for in vivo characterization of corneal biomechanical properties.