The method for determining intraocular pressure according to keratotopographic indicators

Abstract

Relevance. In most countries of the world, applanation tonometers remain popular, such as the Maklakov tonometer and the Goldman tonometer. When measuring ophthalmotonus, such tonometers receive IOP values indirectly through the cornea, which certainly introduces its own errors into the measurement results. The creation of methods for measuring IOP different from the currently existing ones is relevant. Purpose: to create a new method for determining intraocular pressure without tonometry, based on the indicators of the individual profi le of the cornea with its parameters, indices and autorefractometry data. Materials and methods. Statistical analysis of 16 parameters of a keratotopograph (ALLEGRO Oculyzer, WaveLight Oculyzer II), data of an autorefractometer (TONOREF Nidek device) and data of tonometric intraocular pressure was carried out using a Maklakov tonometer (НГм2-«ОФТ-П») in 500 patients (1000 eyes). Among the sample population there were patients with both emmetropic refraction – 8 eyes (0.8%), and patients with refractive errors 992 eyes (99.2%), among them: 978 eyes (97.8%) had myopic refraction, 14 (1.4%) eyes had isolated refraction with myopic astigmatism. 889 eyes (88.9%) combined myopic refraction with myopic astigmatism. Results. Based on the analysis of keratotopographic parameters, autorefractometry values and tonometric IOP of 500 patients (1000 eyes), we have created a new method for determining intraocular pressure without tonometry, presented in the form of a mathematical model: Pt keratotopographic = 61.9 – 0.06 × SPH – 2.39 × Rf + 0.64 × Rmin – 0.15 × log2 (IVA) – 31.9 × CKI – 0.006 × Thickness. Conclusions. Based on the results obtained for determining IOP without physical interaction with the eye, the mathematical model created by us can be used in cases where the use of any tonometer is impossible.