Corneal stiffness and tonometric measurements of IOP
Accurate measurement of intraocular pressure is important for glaucoma management. The clinical standard, Goldmann applanation tonometry is known to be affected by corneal thickness and potentially other corneal factors. This study investigates how corneal stiffness may affect the accuracy of Goldmann tonometric measurement of intraocular pressure.
The intraocular pressure (IOP) is an important parameter that physicians measure in order to make diagnostic and treatment decisions for glaucoma suspects and patients. Goldmann applanation tonometry is accepted as the clinical standard for measuring IOP. Nevertheless, it is known that this device may not be accurate for some subjects whose corneal properties are different from the average of the population. We have theoretically analyzed the measurement procedure and found that potentially significant errors could be present in the measurements due to the variance of corneal properties. For example, thick and stiff corneas may lead to an overestimation of IOP while thin and soft corneas may lead to underestimation. This application will study how the stiffness of the cornea could affect the accuracy of Goldmann tonometry. Our laboratory has developed a non-invasive method that allows us to measure corneal stiffness in humans in a safe and convenient way. With this technique and other experimental tools we have assembled, we are studying: 1. the influence of corneal stiffness on the accuracy of IOP measurements in an experimental porcine (pig) eye model, 2. the influence of corneal stiffness on the accuracy of IOP measurement in human donor eyes, and 3. the effect of corneal stiffness on clinical IOP measurement. These studies will help us better understand the impact of corneal properties on the measurement of IOP, and lead to more accurate methods for monitoring IOP during the course of glaucoma diagnosis and treatment.