Intraocular Pressure: Goldmann Tonometry, Computational Model, and Calibration Equation

Abstract

It has been shown for some time that several visual pathologies are the result of special conditions of geometry (ECR: External Curvature Radius, CCT: Central Corneal Thickness), mechanical properties (E: Young's modulus), and intraocular pressure (IOP). There is one weakness on diagnosis of these pathologies related to the determining of true IOP. On this measure, it is questioning its validity with any type of tonometer and especially with Goldmann Applanation Tonometer (GAT), because it is calibrated for adult healthy eyes. In this work, the calibration of the measurements of the IOP through GAT is done using a simulation of mechanical corneal behaviour through the applanation process using the method of the finite element modeling. This methodology is follow for establishing the range of real IOP readings of patients to obtain a reliable measure of pressure. From statistical variable analysis point of view, supported on computational modelling, a calibration equation is established for the device that relates the true IOP with the ECR, ECC and GAT measurement, subject to a range of application.