Measurements of ocular properties in response to intraocular pressure changes using an ultrasonic system

An ultrasonic system was developed to measure the biomechanical properties of intact corneas and determine the effects of an elevated intraocular pressure (IOP) on these properties. Accurate measurement of IOP is essential for early detection of blinding disease, glaucoma. Inter-subject variations of biomechanical properties may have introduced significant errors to IOP measurements using the current gold standard - Goldmann applanation tonometry. Therefore, it is important to develop a non-invasive method for measuring corneal biomechanical properties in vivo. In this study, an ultrasonic measurement technique in combination with a mathematical model for wave propagation in thin layers was developed to estimate cornea! properties and to differentiate the changes of the corneal properties in response to IOP changes in five enucleated porcine eyes. The measurements were performed with the IOPs adjusted at three different levels. Results showed that the ultrasonic method was sensitive to corneal property changes associated with IOP changes. We concluded that the ultrasonic method has the potential to implement non-invasive measurements of corneal properties in vivo.