Methods for measuring intraocular pressure: disadvantages and advantages

BACKGROUND: Measurement of intraocular pressure in the presence of combined ophthalmic condition could determine further therapy and prognosis. However, tonometry in corneal diseases could lead to unreliable results. The search for methods for intraocular pressure measurement in these settings is a critical task intended to expand diagnostic capabilities. AIM: Evaluation of the transpalpebral tonometry diagnostic value for intraocular pressure monitoring in patients with corneal conditions of various origin. MATERIALS AND METHODS: Measurements of intraocular pressure were carried out in 39 patients with glaucoma and/or cataract (mean age 62.34 9.1), with corneal changes due to various ophthalmic conditions: post-traumatic scars; keratotomy scars as a result of refractive surgery; corneal defects due to ulcerative process of various etiology; corneal erosions; bullous keratopathy; deformities and leukomas after surgical treatment of pterygium or exposure to an infectious agent. Intraocular pressure measurement was carried out using several methods: palpation, using rebound and transpalpebral tonometry, in some cases tonometry was performed according to Maklakov method. RESULTS: The averaged data were comparable: palpation; rebound tonometry 23.34 4.7 mm Hg; transpalpebral tonometry 24.27 4.7 mm Hg; and Maklakov tonometry 23.16 5.4 mm Hg. The accuracy and reproducibility of measurement results increased significantly with the improvement of skills in using tonometers. CONCLUSIONS: Transpalpebral tonometry using TVGD-02 tonometer makes it possible to adequately assess intraocular pressure in patients with corneal pathology. The absence of contact during the implementation of technique makes it possible to recognize it as a priority when measuring intraocular pressure in certain categories of patients.

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Transpalpebral tonometry as a priority method for intraocular pressure monitoring in corneal pathology

Petrov

Филиппова

Markelova

2023

Ophthalmology Reports

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Analysis of the effect of keratotopographic parameters on tonometric intraocular pressure

Ahmetov,

Samoylov,

Usov

2024

Ophthalmology Reports

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BACKGROUND: Applanation tonometers remain popular in most countries of the world; in Russia, the Maklakov tonometer is one of them. When using a Maklakov tonometer, intraocular pressure values are obtained indirectly through the cornea, which has individual characteristics, which certainly introduces its own errors into the accuracy of the measurement results. AIM: The aim of this study was to investigate the influence of keratotopographic parameters on tonometric intraocular pressure. MATERIALS AND METHODS: A study of 16 keratotopographic indices (using ALLEGRO Oculyzer Wavelight Oculyzer II) and of tonometric intraocular pressure values obtained using Maklakov tonometer (NGm2-“OFT-P”) was carried out in 500 patients (1000 eyes). Among the study 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 16 keratotopographic parameters and tonometric intraocular pressure values, 500 patients (1000 eyes), the greatest influence of 13 studied parameters of the cornea was determined, such as: K1 (keratometry of flatter meridian); K2 (keratometry of steeper meridian); Km (mean keratometry); Rf (radius of the flatter meridian); Rs (radius of the steeper meridian); Rm (mean radius of curvature); Rmin (minimal radius of curvature); Rper (average radius of curvature between the 6 mm and 9 mm zone center); IVA (index of vertical asymmetry); ISV (index of surface variance); CKI (central keratoconus index); Thickness (thickness); IHD (index of height decentration) — on intraocular pressure values. CONCLUSIONS: Based on the results obtained, we determined the effect of topographic parameters of the cornea on tonometric intraocular pressure, and created a formula for correcting intraocular pressure values based on the original formula we developed: Pt keratotopographic corrected = Pt + (±ISVp) + (±IVAp) + (±Rmp) + (±Kmp) + (±CKIp) + (±Thicknessp), where Pt keratotopographic corrected is the corrected tonometric intraocular pressure and Pt is the tonometric intraocular pressure.

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The method for determining intraocular pressure according to keratotopographic indicators

Ahmetov,

Samoylov,

Usov

2023

jour

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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.

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Methods for measuring intraocular pressure: disadvantages and advantages

Cited by 3 publications

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Transpalpebral tonometry as a priority method for intraocular pressure monitoring in corneal pathology

Transpalpebral tonometry as a priority method for intraocular pressure monitoring in corneal pathology

Analysis of the effect of keratotopographic parameters on tonometric intraocular pressure

The method for determining intraocular pressure according to keratotopographic indicators

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