On the enhancement of tonometry informative value

Abstract

The effect of the tonometer contact surface shape on the accuracy of measuring the true and tonometric pressures is analyzed. Possible modifications of the tonometry method, which can not only make the intraocular pressure measurement more accurate but also enable us to estimate parameters characterizing the elastic properties of the corneal and scleral eye segments, Ec and Es, are discussed. The tonometers with flat (Maklakov's method) and convex (convex-tonometry) contact surfaces are taken as examples. It is shown that the pressure measurement accuracy can be increased substantially with increase in the accuracy of the tonometer contact area radius measurement and if the individual Ec and Es values are attained from independent measurements. Possible measurement modification methods which make it possible to estimate together the individual values of the intraocular pressure and the parameters Ec and Es that separately characterize the elastic properties of the cornea and the scleral segment. The tonometry modification consists in measuring within each examination the intraocular pressure by the standard method using successively both tonometers considered, of two different weights each (four measurements). The complication of the measurement procedure is justified not only by the possibility to increase the intraocular pressure measurement accuracy but also by the possibility to simultaneously estimate the individual elastic characteristics of the cornea and the scleral segment, which may be important for diagnostics and therapeutic efficacy control.