# Experimental Assessment of the Spatial and Temporal Distribution of Non-Contact Tonometer Airflows
###### 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 \(\upmu\)m and a 1 mm resolution grid, respectively. (3) Central airflow pressure of the CorvisST (96.4 \(\pm\) 1.4 mmHg) was higher than that of the Ocular Response Analyser (91.7 \(\pm\) 0.7 mmHg). The duration of the air-puffs also differed, with the CorvisST showing a shorter duration (21.483 \(\pm\) 0.2881 ms) than that of the ORA (23.061 \(\pm\) 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.  
air puff; CorvisST; ORA; airflow pressure of NCT; physical dimension of jet stream; temporal and spatial distribution of the air puff  
25 January 2021  
6 March 2021  
11 March 2021  
###### Abstract  
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 \(\upmu\)m and a 1 mm resolution grid, respectively. (3) Central airflow pressure of the CorvisST (96.4 \(\pm\) 1.4 mmHg) was higher than that of the Ocular Response Analyser (91.7 \(\pm\) 0.7 mmHg). The duration of the air-puffs also differed, with the CorvisST showing a shorter duration (21.483 \(\pm\) 0.2881 ms) than that of the ORA (23.061 \(\pm\) 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.  
Keywords:air puff; CorvisST; ORA; airflow pressure of NCT; physical dimension of jet stream; temporal and spatial distribution of the air puff +
Footnote †: journal: Applied Sciences