Does air gas aesthesiometry generate a true mechanical stimulus for corneal sensitivity measurement?

Nosch, Daniela S, Pult, Heiko ORCID: https://orcid.org/0000-0003-4371-8007, Albon, Julie ORCID: https://orcid.org/0000-0002-3029-8245, Purslow, Christine and Murphy, Paul J 2018. Does air gas aesthesiometry generate a true mechanical stimulus for corneal sensitivity measurement? Clinical and Experimental Optometry 101 (2) , pp. 193-199. 10.1111/cxo.12603

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Abstract

Background: Belmonte Ocular Pain Meter (OPM) air jet aesthesiometry overcomes some of the limitations of the Cochet-Bonnet aesthesiometer. However, for true mechanical corneal sensitivity measurement, the airflow stimulus temperature of the aesthesiometer must equal ocular surface temperature (OST), to avoid additional response from temperature-sensitive nerves. The aim of this study was to determine: (A) the stimulus temperature inducing no or least change in OST; and (B) to evaluate if OST remains unchanged with different stimulus durations and airflow rates. Methods: A total of 14 subjects (mean age 25.14 2.18 years; seven women) participated in this clinical cohort study: (A) OST was recorded using an infrared camera (FLIR A310) during the presentation of airflow stimuli, at five temperatures, ambient temperature (AT) +5C, +10C, +15C, +20C and +30C, using the OPM aesthesiometer (duration three seconds; over a four millimetre distance; airflow rate 60 ml/min); and (B) OST measurements were repeated with two stimulus temperatures (AT +10C and +15C) while varying stimulus durations (three seconds and five seconds) and airflow rates (30, 60, 80 and 100 ml/min). Inclusion criteria were age <40 years, no contact lens wear, absence of ocular disease including dry eye, and no use of artificial tears. Repeated measures (analysis of variance) and appropriate post-hoc t-tests were applied. Results: (A) Stimulus temperatures of AT +10C and +15C induced the least changes in OST (−0.20 0.13C and 0.08 0.05C). (B) OST changes were statistically significant with both stimulus temperatures and increased with increasing airflow rates (p < 0.001), and were more marked with stimulus temperature AT +10C. Conclusion: A true mechanical threshold for corneal sensitivity cannot be established with the air stimulus of the Belmonte OPM because its air jet stimulus with mechanical setting is likely to have a thermal component. Appropriate stimulus selection for an air jet aesthesiometer must incorporate stimulus temperature control that can vary with stimulus duration and airflow rate.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Optometry and Vision Sciences
Publisher:	Wiley: 12 months
ISSN:	0816-4622
Date of First Compliant Deposit:	13 September 2018
Date of Acceptance:	10 June 2017
Last Modified:	22 May 2024 15:02
URI:	https://orca.cardiff.ac.uk/id/eprint/114877

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