Abstract
(1) The aim of the study was to investigate the spatial and temporal characteristics of the airflow created by two commercially available non-contact tonometers: the CorvisST and the Ocular Response Analyser (ORA). (2) The airflow pressure was measured using a microelectromechanical system (MEMS) pressure sensor to investigate the spatial and temporal distribution. The airflow from the CorvisST and Ocular Response Analyser were mapped to a 600 µm and a 1 mm resolution grid, respectively. (3) Central airflow pressure of the CorvisST (96.4 ± 1.4 mmHg) was higher than that of the Ocular Response Analyser (91.7 ± 0.7 mmHg). The duration of the air-puffs also differed, with the CorvisST showing a shorter duration (21.483 ± 0.2881 ms) than that of the ORA (23.061 ± 0.1872 ms). The rising edge of the CorvisST airflow pressure profile demonstrated a lower gradient (+8.94 mmHg/ms) compared to that of the Ocular Response Analyser (+11.00 mmHg/ms). Both had similar decay response edges: CorvisST −11.18 mmHg/ms, Ocular Response Analyser −11.65 mmHg/ms. (4) The study presents a valid method to investigate the physical dimensions of the airflow pressure of non-contact tonometers. Novel findings relating to the magnitude, duration and spatial characteristics of the respective airflow pressures are reported. It is anticipated that this information will better inform clinical studies and theoretical models relating to ocular biomechanics.
Highlights
Limitations relating to the influence of corneal biomechanics on the intraocular pressure (IOP) measurements are well recognised with all tonometric tests
Ocular Response Analyser (ORA) are based upon the application of known forces to the cornea, there is still no comprehensive evidence available about the spatial distribution, magnitude and duration of the airflow pressure generated by these devices
Understanding the fundamental physical characteristics of the airflow pressures produced by non-contact tonometers is vital when interpreting measures of IOP and corneal biomechanics
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Tonometers are used to measure the eye’s intraocular pressure (IOP). These tonometers vary in design, but all are based on measuring the force needed to applanate or indent a given surface area of the cornea to infer the pressure within the eye. Limitations relating to the influence of corneal biomechanics on the IOP measurements are well recognised with all tonometric tests. To overcome some of these, a non-contact air-puff tonometers such as the CorvisST (Oculus Optikgeräte GmbH; Wetzlar, Germany) and the Reichert Ocular
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